feat(deps): bump github.com/aws/aws-sdk-go-v2/config from 1.28.4 to 1.28.5 (#223)

Bumps
[github.com/aws/aws-sdk-go-v2/config](https://github.com/aws/aws-sdk-go-v2)
from 1.28.4 to 1.28.5.
<details>
<summary>Commits</summary>
<ul>
<li><a
href="d125de3792"><code>d125de3</code></a>
Release 2024-11-18</li>
<li><a
href="fec51f3fff"><code>fec51f3</code></a>
Regenerated Clients</li>
<li><a
href="fba5997045"><code>fba5997</code></a>
Update API model</li>
<li><a
href="0b8e5c842f"><code>0b8e5c8</code></a>
Bump smithy-go dependency (<a
href="https://redirect.github.com/aws/aws-sdk-go-v2/issues/2902">#2902</a>)</li>
<li><a
href="50ba45ce16"><code>50ba45c</code></a>
Release 2024-11-15.2</li>
<li><a
href="444bdffccd"><code>444bdff</code></a>
Regenerated Clients</li>
<li><a
href="55ab381b20"><code>55ab381</code></a>
Update endpoints model</li>
<li><a
href="94c083768b"><code>94c0837</code></a>
Update API model</li>
<li><a
href="2398a7903c"><code>2398a79</code></a>
Remove elastictranscoder service's integration test (<a
href="https://redirect.github.com/aws/aws-sdk-go-v2/issues/2901">#2901</a>)</li>
<li><a
href="93e0f294f6"><code>93e0f29</code></a>
Release 2024-11-15</li>
<li>Additional commits viewable in <a
href="https://github.com/aws/aws-sdk-go-v2/compare/config/v1.28.4...config/v1.28.5">compare
view</a></li>
</ul>
</details>
<br />


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Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/ISSUE_TEMPLATE/bug-report.md

@@ -0,0 +1,19 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ""
+labels: bug
+assignees: ""
+---
+
+**What steps did you take and what happened:**
+[A clear and concise description of what the bug is.]
+
+**What did you expect to happen:**
+
+**Anything else you would like to add:**
+[Miscellaneous information that will assist in solving the issue.]
+
+**Environment:**
+
+- Attest version:

.github/ISSUE_TEMPLATE/feature-request.md

@@ -0,0 +1,13 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ""
+labels: enhancement
+assignees: ""
+---
+
+**Describe the solution you'd like**
+[A clear and concise description of what you want to happen.]
+
+**Anything else you would like to add:**
+[Miscellaneous information that will assist in solving the issue.]

.github/PULL_REQUEST_TEMPLATE.md

@@ -0,0 +1,11 @@
+## Summary
+
+<!-- Description of why the pull request is needed and what it changes -->
+
+### Tests
+
+<!-- Provide evidence of testing -->
+
+### Issue
+
+<!-- Link to issue that this is part of -->

.github/dco.yml

@@ -0,0 +1,2 @@
+require:
+  members: false

.github/release-drafter-config.yml

@@ -14,6 +14,9 @@ categories:
   - title: "🧰 Maintenance"
     labels:
       - "chore"
+  - title: "💥 Breaking Changes"
+    labels:
+      - "breaking"
 
 change-template: "- $TITLE @$AUTHOR (#$NUMBER)"
 change-title-escapes: '\<*_&' # You can add # and @ to disable mentions, and add ` to disable code blocks.
@@ -21,6 +24,7 @@ version-resolver:
   major:
     labels:
       - "major"
+      - "breaking"
   minor:
     labels:
       - "minor"
@@ -37,26 +41,19 @@ autolabeler:
   - label: "chore"
     files:
       - "*.md"
-    branch:
-      - '/docs{0,1}\/.+/'
-      - '/tests{0,1}\/.+/'
-      - '/chore{0,1}\/.+/'
     title:
-      - "/docs/i"
-      - "/test/i"
-      - "/chore/i"
+      - "/^docs!?:/i"
+      - "/^test!?:/i"
+      - "/^chore!?:/i"
+      - "/^refactor!?:/i"
   - label: "bug"
-    branch:
-      - '/fix\/.+/'
-      - '/revert\/.+/'
     title:
-      - "/fix/i"
-      - "/revert/i"
+      - "/^fix!?:/i"
+      - "/^revert!?:/i"
   - label: "feature"
-    branch:
-      - '/feature\/.+/'
-      - '/feat\/.+/'
-      - '/add\/.+/'
     title:
-      - "/feat/i"
-      - "/add/i"
+      - "/^feat!?:/i"
+      - "/^add!?:/i"
+  - label: "breaking"
+    title:
+      - "/^[a-zA-Z]+!:/i"

.github/workflows/lint.yml

@@ -0,0 +1,19 @@
+name: lint code
+on:
+  pull_request:
+  workflow_dispatch:
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Set git to use LF
+        run: git config --global core.autocrlf false
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version: 1.22.x
+      - name: golangci-lint
+        uses: golangci/golangci-lint-action@v6
+        with:
+          version: v1.59
+          only-new-issues: true

.github/workflows/release.yml

@@ -0,0 +1,24 @@
+name: release
+on:
+  release:
+    types: [published]
+jobs:
+  trigger_attest_update:
+    name: Update attest lib - ALL
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+    steps:
+      - name: Generate GitHub App Token
+        id: app-token
+        uses: actions/create-github-app-token@5d869da34e18e7287c1daad50e0b8ea0f506ce69 # v1.11.0
+        with:
+            app-id: ${{ vars.ATTEST_RELEASE_APP_ID }}
+            private-key: ${{ secrets.ATTEST_RELEASE_APP_PRIVATE_KEY }}
+            repositories: "attest-actions"
+      - name: Send repository_dispatch event
+        uses: peter-evans/repository-dispatch@v3.0.0
+        with:
+          token: ${{ steps.app-token.outputs.token }}
+          event-type: update_attest_all
+          repository: docker/attest-actions
+          client-payload: '{"attest_version": "${{ github.ref_name }}"}'

.github/workflows/test.yml

@@ -7,9 +7,12 @@ on:
   workflow_dispatch:
 jobs:
   golang:
+    permissions:
+      contents: read
+      id-token: write
     strategy:
       matrix:
-        go-version: [1.21.x]
+        go-version: [1.22.x, 1.23.x]
         # temp disable windows tests see https://github.com/docker/image-signer-verifier/pull/154
         # os: [ubuntu-latest, macos-latest, windows-latest]
         os: [ubuntu-latest, macos-latest]
@@ -21,9 +24,42 @@ jobs:
       - uses: actions/setup-go@v5
         with:
           go-version: ${{ matrix.go-version }}
+      - name: Login to Docker Hub
+        if: matrix.os == 'ubuntu-latest' && github.actor != 'dependabot[bot]'
+        uses: docker/login-action@v3
+        with:
+          username: dockerpublicbot
+          password: ${{ secrets.DOCKERPUBLICBOT_WRITE_PAT }}
+      - name: Authenticate to AWS
+        if: matrix.os == 'ubuntu-latest' && github.actor != 'dependabot[bot]'
+        uses: aws-actions/configure-aws-credentials@e3dd6a429d7300a6a4c196c26e071d42e0343502 #v4.0.2
+        with:
+          aws-region: "us-east-1"
+          role-to-assume: arn:aws:iam::175142243308:role/doi-github-actions-signing
+      - name: auth-with-gcp
+        if: matrix.os == 'ubuntu-latest' && github.actor != 'dependabot[bot]'
+        uses: google-github-actions/auth@v2
+        with:
+          project_id: 'attest-kms-test'
+          export_environment_variables: true
+          workload_identity_provider: 'projects/385966116051/locations/global/workloadIdentityPools/attest-kms-test/providers/attest-kms-test'
+          service_account: 'attest-kms-test@attest-kms-test.iam.gserviceaccount.com'
       - name: Setup Testcontainers Cloud Client
         uses: atomicjar/testcontainers-cloud-setup-action@v1
         with:
           token: ${{ secrets.TC_CLOUD_TOKEN }}
-      - name: go test
-        run: go test ./...
+      - name: go test including e2e
+        if: matrix.os == 'ubuntu-latest' && github.actor != 'dependabot[bot]'
+        run: go test -tags=e2e -v ./... -coverpkg=./... -coverprofile=coverage.out -covermode=atomic
+      - name: go test excluding e2e
+        if: matrix.os == 'macos-latest' || github.actor == 'dependabot[bot]'
+        run: go test -v ./...
+      - name: Upload coverage to Codecov
+        if: matrix.os == 'ubuntu-latest' && github.actor != 'dependabot[bot]'
+        uses: codecov/codecov-action@v5
+        with:
+          file: ./coverage.out
+          flags: unittests
+          name: codecov-umbrella
+          fail_ci_if_error: true
+          token: ${{ secrets.CODECOV_TOKEN }}

.gitignore

@@ -19,3 +19,4 @@
 
 # Go workspace file
 go.work
+.aider*

.golangci.yaml

@@ -0,0 +1,36 @@
+run:
+  timeout: 5m
+  go: "1.22"
+
+linters-settings:
+  gocritic:
+    enabled-tags:
+      - performance
+  lll:
+    line-length: 200
+
+  misspell:
+    locale: US
+
+linters:
+  disable-all: true
+  enable:
+    - errcheck
+    - forcetypeassert
+    - gocritic
+    - goconst
+    - godot
+    - gofmt
+    - gofumpt
+    - goimports
+    - gosec
+    - gosimple
+    - govet
+    - importas
+    - ineffassign
+    - misspell
+    - revive # replacement for golint
+    - staticcheck
+    - typecheck
+    - unused
+    - whitespace

CODE-OF-CONDUCT.md

@@ -0,0 +1,131 @@
+# Contributor Covenant Code of Conduct
+
+## Our Pledge
+
+We as members, contributors, and leaders pledge to make participation in our
+community a harassment-free experience for everyone, regardless of age, body
+size, visible or invisible disability, ethnicity, sex characteristics, gender
+identity and expression, level of experience, education, socio-economic status,
+nationality, personal appearance, race, religion, or sexual identity
+and orientation.
+
+We pledge to act and interact in ways that contribute to an open, welcoming,
+diverse, inclusive, and healthy community.
+
+## Our Standards
+
+Examples of behavior that contributes to a positive environment for our
+community include:
+
+* Demonstrating empathy and kindness toward other people
+* Being respectful of differing opinions, viewpoints, and experiences
+* Giving and gracefully accepting constructive feedback
+* Accepting responsibility and apologizing to those affected by our mistakes,
+  and learning from the experience
+* Focusing on what is best not just for us as individuals, but for the
+  overall community
+
+Examples of unacceptable behavior include:
+
+* The use of sexualized language or imagery, and sexual attention or
+  advances of any kind
+* Trolling, insulting or derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or email
+  address, without their explicit permission
+* Other conduct which could reasonably be considered inappropriate in a
+  professional setting
+
+## Enforcement Responsibilities
+
+Community leaders are responsible for clarifying and enforcing our standards of
+acceptable behavior and will take appropriate and fair corrective action in
+response to any behavior that they deem inappropriate, threatening, offensive,
+or harmful.
+
+Community leaders have the right and responsibility to remove, edit, or reject
+comments, commits, code, wiki edits, issues, and other contributions that are
+not aligned to this Code of Conduct, and will communicate reasons for moderation
+decisions when appropriate.
+
+## Scope
+
+This Code of Conduct applies within all community spaces, and also applies when
+an individual is officially representing the community in public spaces.
+Examples of representing our community include using an official email address,
+posting via an official social media account, or acting as an appointed
+representative at an online or offline event.
+
+## Enforcement
+
+Instances of abusive, harassing, or otherwise unacceptable behavior may be
+reported by submitting an [incident report](https://docs.google.com/forms/d/e/1FAIpQLScezna1ZXRPzC_phSDoPEF4c5nvw8yQW-vvtI8xHjv-BB9MOg/viewform?c=0&w=1).
+All complaints will be reviewed and investigated promptly and fairly.
+
+All community leaders are obligated to respect the privacy and security of the
+reporter of any incident.
+
+## Enforcement Guidelines
+
+Community leaders will follow these Community Impact Guidelines in determining
+the consequences for any action they deem in violation of this Code of Conduct:
+
+### 1. Correction
+
+**Community Impact**: Use of inappropriate language or other behavior deemed
+unprofessional or unwelcome in the community.
+
+**Consequence**: A private, written warning from community leaders, providing
+clarity around the nature of the violation and an explanation of why the
+behavior was inappropriate. A public apology may be requested.
+
+### 2. Warning
+
+**Community Impact**: A violation through a single incident or series
+of actions.
+
+**Consequence**: A warning with consequences for continued behavior. No
+interaction with the people involved, including unsolicited interaction with
+those enforcing the Code of Conduct, for a specified period of time. This
+includes avoiding interactions in community spaces as well as external channels
+like social media. Violating these terms may lead to a temporary or
+permanent ban.
+
+### 3. Temporary Ban
+
+**Community Impact**: A serious violation of community standards, including
+sustained inappropriate behavior.
+
+**Consequence**: A temporary ban from any sort of interaction or public
+communication with the community for a specified period of time. No public or
+private interaction with the people involved, including unsolicited interaction
+with those enforcing the Code of Conduct, is allowed during this period.
+Violating these terms may lead to a permanent ban.
+
+### 4. Permanent Ban
+
+**Community Impact**: Demonstrating a pattern of violation of community
+standards, including sustained inappropriate behavior,  harassment of an
+individual, or aggression toward or disparagement of classes of individuals.
+
+**Consequence**: A permanent ban from any sort of public interaction within
+the community.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 2.0, available at
+[https://www.contributor-covenant.org/version/2/0/code_of_conduct.html][v2.0].
+
+Community Impact Guidelines were inspired by 
+[Mozilla's code of conduct enforcement ladder][Mozilla CoC].
+
+For answers to common questions about this code of conduct, see the FAQ at
+[https://www.contributor-covenant.org/faq][FAQ]. Translations are available 
+at [https://www.contributor-covenant.org/translations][translations].
+
+[homepage]: https://www.contributor-covenant.org
+[v2.0]: https://www.contributor-covenant.org/version/2/0/code_of_conduct.html
+[Mozilla CoC]: https://github.com/mozilla/diversity
+[FAQ]: https://www.contributor-covenant.org/faq
+[translations]: https://www.contributor-covenant.org/translations

CONTRIBUTING.md

@@ -0,0 +1,85 @@
+# Contribute to the attest Library
+
+Want to hack on the attest library? This guide will help you to find out how to contribute.
+
+This page contains information about reporting issues as well as some tips and guidelines useful to experienced open source contributors. Finally, make sure you read our [community guidelines](#community-guidelines) before you start participating.
+
+## Topics
+
+* [Reporting Security Issues](#reporting-security-issues)
+* [Design and Cleanup Proposals](#design-and-cleanup-proposals)
+* [Reporting Issues](#reporting-other-issues)
+* [Quick Contribution Tips and Guidelines](#quick-contribution-tips-and-guidelines)
+* [Community Guidelines](#community-guidelines)
+
+## Reporting security issues
+
+The attest maintainers take security seriously. If you discover a security issue, please bring it to their attention right away!
+
+Please **DO NOT** file a public issue, instead send your report privately to [security@docker.com](mailto:security@docker.com).
+
+Security reports are greatly appreciated and we will publicly thank you for it, although we keep your name confidential if you request it. We also like to send gifts—if you're into schwag, make sure to let us know. We currently do not offer a paid security bounty program, but are not ruling it out in the future.
+
+## Reporting other issues
+
+A great way to contribute to the project is to send a detailed report when you encounter an issue. We always appreciate a well-written, thorough bug report, and will thank you for it!
+
+Check that [our issue database](https://github.com/docker/attest/issues) doesn't already include that problem or suggestion before submitting an issue. If you find a match, you can use the "subscribe" button to get notified on updates. Do *not* leave random "+1" or "I have this too" comments. Those comments can become annoying very quickly. Instead, use [GitHub reactions](https://docs.github.com/en/free-pro-team@latest/github/writing-on-github/using-emojis).
+
+### How to report a bug
+
+* **Use a clear and descriptive title** for the issue to identify the problem.
+* **Describe the exact steps which reproduce the problem** in as many details as possible. When listing steps, **don't just say what you did, but explain how you did it**.
+* **Provide specific examples to demonstrate the steps**. Include links to files or GitHub projects, or copy/pasteable snippets, which you use in those examples. If you're providing snippets in the issue, use [Markdown code blocks](https://help.github.com/articles/markdown-basics/#multiple-lines).
+* **Describe the behavior you observed after following the steps** and point out what exactly is the problem with that behavior.
+* **Explain which behavior you expected to see instead and why.**
+* **Include screenshots and animated GIFs** which show you following the described steps and clearly demonstrate the problem.
+* **If the problem is related to performance or memory**, include a [CPU profile capture](https://blog.golang.org/profiling-go-programs) with your report.
+* **If the problem wasn't triggered by a specific action**, describe what you were doing before the problem happened.
+* **Include the version of attest you are using**.
+* **Include the name and version of the OS you're using**.
+
+## Quick contribution tips and guidelines
+
+This section gives a brief overview of how to propose a change to attest.
+
+### Contribution flow
+
+1. Fork the repository on GitHub.
+2. Create a topic branch from where you want to base your work.
+3. Make commits of logical units.
+4. Make sure your commit messages are in the proper format (see below).
+5. Push your changes to a topic branch in your fork of the repository.
+6. Submit a pull request to the original repository.
+
+### Format of the commit message
+
+We follow a rough convention for commit messages [borrowed from Angular](https://www.conventionalcommits.org/en/v1.0.0/).
+
+- **feat**: A new feature
+- **fix**: A bug fix
+- **docs**: Documentation only changes
+- **style**: Changes that do not affect the meaning of the code (white-space, formatting, missing semi-colons, etc)
+- **refactor**: A code change that neither fixes a bug nor adds a feature
+- **perf**: A code change that improves performance
+- **test**: Adding missing or correcting existing tests
+- **chore**: Changes to the build process or auxiliary tools and libraries such as documentation generation
+
+### Code review process
+
+All submissions, including submissions by project members, require review. We use GitHub pull requests for this purpose.
+
+### Tips for contributors
+
+1. All code should be formatted with `gofmt -s`.
+2. All code should pass the default levels of [`golint`](https://github.com/golang/lint).
+3. All code should follow the guidelines covered in [Effective Go](http://golang.org/doc/effective_go.html) and [Go Code Review Comments](https://github.com/golang/go/wiki/CodeReviewComments).
+4. Comment the code. Tell us the why, the history, and the context.
+5. Document _all_ public declarations and methods. Declare expectations, caveats, and anything else that may be important. If a type gets exported, having the comments already there will ensure it's ready.
+6. Variable name length should be proportional to its context and no longer. `noCommaALongVariableNameLikeThisIsNotMoreClearWhenASimpleCommentWouldDo`. In practice, short methods will have short variable names and globals will have longer names.
+7. No underscores in package names. If you need a compound name, step back, and re-examine why you need a compound name. If you still think you need a compound name, lose the underscore.
+8. No utils or helpers packages. If a function is not general enough to warrant its own package, it has not been written generally enough to be a part of a util package. Just leave it unexported and well-documented.
+9. All tests should run with `go test` and outside tooling should not be required. No, we don't need another unit testing framework.
+10. Even though we call these "rules" above, they are actually just guidelines. Since you've read all the rules, you now know that.
+
+If you are having trouble getting into the mood of idiomatic Go, we recommend reading through [Effective Go](https://go.dev/doc/effective_go). The [Go Blog](https://go.dev/blog/) is also a great resource. Drinking the kool-aid is a lot easier than going thirsty.

NOTICE

@@ -0,0 +1,15 @@
+Docker attest
+Copyright Docker attest authors
+
+This product includes software developed at Docker, Inc. (https://www.docker.com).
+
+The following is courtesy of our legal counsel:
+
+Use and transfer of Docker may be subject to certain restrictions by the
+United States and other governments.
+It is your responsibility to ensure that your use and/or transfer does not
+violate applicable laws.
+
+For more information, please see https://www.bis.doc.gov
+
+See also https://www.apache.org/dev/crypto.html and/or seek legal counsel.

README.md

@@ -1,2 +1,382 @@
-# attest
-Library to create, verify, and evaluate policy for attestations on container images
+# `attest`
+
+<div align="center">
+Library to create attestation signatures on container images, and verify images against policy.
+
+[![Go Reference](https://pkg.go.dev/badge/github.com/docker/attest.svg)](https://pkg.go.dev/github.com/docker/attest)
+[![GitHub Workflow Status](https://img.shields.io/github/actions/workflow/status/docker/attest/test.yml?branch=main)](https://github.com/docker/attest/actions/workflows/test.yml)
+[![codecov](https://codecov.io/gh/docker/attest/graph/badge.svg?token=cGT0f1ACKg)](https://codecov.io/gh/docker/attest)
+
+</div>
+
+# Table of Contents
+
+- [`attest`](#attest)
+- [Table of Contents](#table-of-contents)
+- [What is this?](#what-is-this)
+- [Features](#features)
+- [Installation](#installation)
+- [Usage](#usage)
+  - [Verifying Image Attestations](#verifying-image-attestations)
+  - [Signing Attestations](#signing-attestations)
+- [Rego Policy](#rego-policy)
+  - [Writing Policy](#writing-policy)
+    - [Input](#input)
+    - [Builtin Functions](#builtin-functions)
+  - [Policy Mapping](#policy-mapping)
+- [Public Key IDs](#public-key-ids)
+- [Transparency Logging](#transparency-logging)
+- [Verification Summary Attestation (VSA)](#verification-summary-attestation-vsa)
+  - [Example VSA](#example-vsa)
+- [API Reference](#api-reference)
+- [Project Layout](#project-layout)
+- [Versioning](#versioning)
+
+# What is this?
+
+`attest` is a library for signing and verifying [in-toto](https://in-toto.io/) attestations on container images.
+Examples of attestations include statements about the provenance and SBOM of an image.
+
+This library can be used to verify these attestations using Rego policy.
+Policy can be used to check whether an attestation is correctly signed, and that the contents of the attestation are correct.
+
+# Features
+
+- Sign in-toto attestations
+- Push attestations to container registries using OCI 1.1 compatible artifacts
+- Verify attestations on container images using Rego policy and attestations fetched using OCI 1.1 referrers
+
+# Installation
+
+```shell
+$ go get github.com/docker/attest
+```
+
+# Usage
+
+## Verifying Image Attestations
+
+An image's attestations can be verified against a policy using the `attest.Verify` function.
+This function takes an [oci.ImageSpec](https://github.com/docker/attest/blob/781a738b54b9549c1dabfd7ea3f7ea582514ddec/pkg/oci/types.go#L35-L41) for the image to verify, and a set of options for policy resolution.
+By default, the policy is resolved from the [the Docker TUF repository](https://github.com/docker/tuf), but the options can be used to specify an alternative TUF repository, a local policy directory, and/or a policy ID to use.
+See [Policy Mapping](#policy-mapping) for more details.
+
+The `attest.Verify` function returns a `VerificationSummary` object, which contains the results of the policy evaluation.
+
+See [example_verify_test.go](./example_verify_test.go) for an example of how to verify an image against a policy.
+
+## Signing Attestations
+
+in-toto statements can be signed directly using the `attestation.SignInTotoStatement` function.
+This function takes a statement and DSSE signer, and returns a signed DSSE envelope containing a copy of the original statement.
+
+For the common use case of signing a statement and adding it to a manifest, e.g. for pushing to a registry as a referrer to the image being attested, the `attestation.AttestationManifest` type can be used.
+See [example_attestation_manifest_test.go](./pkg/attestation/example_attestation_manifest_test.go)
+
+See also [example_sign_test.go](./example_sign_test.go) for an example of how to sign all attached in-toto statements on an image, e.g. those produced by buildkit.
+
+# Rego Policy
+
+An image policy consists of one or more `rego` files and, optionally, `json` or `yaml` data files.
+
+The policies for trusted namespaces `docker.io/docker` and `docker.io/library` are stored in [the Docker TUF root](https://github.com/docker/tuf) under the `docker` and `doi` target sub-directories respectively.
+
+## Writing Policy
+
+`attest` uses [Open Policy Agent](https://www.openpolicyagent.org/) (OPA) for policy evaluation, and policies are written in Rego.
+A full guide to writing Rego policies is available in the [Rego documentation](https://www.openpolicyagent.org/docs/latest/policy-language/).
+
+For attest, a policy must contain at a minimum a `result` rule in a package called `attest` that returns an object matching the schema defined by the [`policy.Result`](https://github.com/docker/attest/blob/bd2c4d7d8aa497754b674412b09628be8d02fab5/pkg/policy/types.go#L23-L27) struct.
+For example:
+
+```rego
+package attest
+
+import rego.v1
+
+result := {
+	"success": true,
+	"violations": set(),
+	"summary": {
+		"subjects": subjects,
+		"slsa_levels": ["SLSA_BUILD_LEVEL_3"],
+		"verifier": "docker-official-images",
+		"policy_uri": "https://docker.com/official/policy/v0.1",
+	},
+}
+```
+
+The meanings of the fields in the `result` object are as follows:
+
+- `success` (bool): whether the policy passes
+- `violations` (set): a set of strings describing any policy violations
+- `summary` (object): a summary of the policy evaluation, used to construct a Verification Summary Attestation (VSA)
+  - `subjects` (set): a set of strings representing the subjects of each attestation that was evaluated
+  - `slsa_levels` (list): a list of strings representing the SLSA levels that the policy complies with
+  - `verifier` (string): the entity that verified the policy
+  - `policy_uri` (string): the URI of the policy
+
+The `violations` set may contain policy violations even if `success` is `true`.
+This can be useful if there are attestations that are invalid, but are not required by the policy.
+
+### Input
+
+The input to the policy is an object with the following fields:
+
+- `digest` (string): the digest of the image being verified
+- `purl` (string): the package URL of the image being verified
+- `platform` (string): the platform of the image being verified
+- `normalized_name` (string): defaults are filled out. e.g. if the image is `alpine`, this would be `library/alpine`
+- `familiar_name` (string): short version of above (e.g. `alpine`)
+- `tag`: (string): tag of the image being verified (if present)
+
+### Builtin Functions
+
+There are two builtin functions provided by `attest` that can be used to help with policy evaluation:
+
+- `attest.fetch(predicate_type)`: fetches all attestations for the input image with the given predicate type.
+  For example, `attest.fetch("https://spdx.dev/Document")` will fetch all SPDX SBOM attestations for the input image.
+- `attest.verify(attestation, options)`: verifies the DSSE envelope of the given attestation, and returns the statement.
+  The options object can contain the following fields:
+  - `keys` (array): keys to use for signature verification. Each key contains the following fields:
+    - `id` (string): the key ID as specified in [Public Key IDs](#public-key-ids)
+    - `key` (string): the PEM-encoded public key
+    - `from` (string): the time from which the key is valid, or `null` if the key was always valid (default: `null`)
+    - `status` (string): `active` if the key is active, otherwise the reason the key is inactive.
+      This is only used in error messages if the `from` date is in the past
+    - `distrust` (bool): whether the key should be distrusted (default: `false`).
+      If `true`, the key will be considered invalid
+    - `signing-format` (string): the format of the signing key, must be `dssev1`
+  - `skip_tl` (bool): whether to skip transparency log entry verification (see [Transparency Logging](#transparency-logging)) (default: `false`)
+
+Both `attest.fetch` and `attest.verify` return an object with the following fields:
+
+- `value`: the return value of the function if successful
+- `error`: an error message if the function failed
+
+This is to allow the policy to easily construct a violation if an error occurs, which isn't usually possible with custom functions in Rego.
+
+The return value of `attest.fetch` is an attestation which can be passed to `attest.verify`.
+
+## Policy Mapping
+
+A `mapping.yaml` file is stored at the root of TUF targets and contains the mapping from repository name to files containing the corresponding policy.
+
+A simple mapping file might look like this:
+
+```yaml
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images
+```
+
+The `policies` section contains a list of policies, each with an `id` and a `description`, and a list of `files` containing the policy.
+The `rules` section contains a list of rules that map regex expressions to policies.
+If the `pattern` regex matches the repository name, the policy with the `policy-id` is used to evaluate the image.
+In the above example, any repository in the `docker.io/library` namespace will be evaluated against the policy in `doi/policy.rego`.
+
+Sometimes it is necessary to rewrite the repository name before evaluating the policy.
+This can be useful when the repository name which is used to reference the image is different from the repository name in the attestations.
+For example, when mirroring images from a public registry to a private registry, the repository name in the attestations will be the public registry, but the image will be referenced by the name of the private registry.
+
+An example of a mapping file with rewrite rules might look like this:
+
+```yaml
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images
+  - pattern: "^public[.]ecr[.]aws/docker/library/(.*)$"
+    platforms: ["linux/amd64"] # optional: restrict image platforms for matching policies (default: all)
+    rewrite: docker.io/library/$1
+```
+`platforms` in the second rule above is optional and can be used to restrict the platforms for which the policy
+ is evaluated. If the `platforms` field is not present, the policy will be applied to all platforms.
+ It's important to note that the `platforms` field is a filter, and is applied before the `pattern`
+ field is processed, so both `platforms` and `pattern` need to match in order for the policy to be selected
+ (or the rewrite to be processed if present).
+
+As before, any repository in the `docker.io/library` namespace will be evaluated against the policy in `doi/policy.rego`.
+The second rule will rewrite any repository in the `public.ecr.aws/docker/library` namespace to `docker.io/library`.
+This means two things:
+
+1. The rules are evaluated again using the rewritten repository name until a policy is found (in this case the first rule will match); and
+2. The rewritten name is passed into the actual policy when it is evaluated.
+
+The `rewrite` field is not a simple string replacement, but a regex replacement.
+This means that the `rewrite` field can contain capture groups that are referenced in the `pattern` field.
+For example, the `rewrite` field in the example above contains `$1`, which is a reference to the first capture group in the `pattern` field.
+
+> [!IMPORTANT]
+> It's important to remember to escape the `.` character in the `pattern` field, as it is a special character in regex.
+> This is why the `.` character is surrounded by `[]` in the example above.
+>
+> It's also important to make use of the `^` and `$` characters in the `pattern` field to ensure that the regex matches the entire repository name.
+> This is to prevent the regex from matching a subset of the repository name, e.g. `docker.io/library` matching `notdocker.io/library`.
+
+Local policy can also be specified via a local `mapping.yaml`, which can be used to create new mirrors of policies described in the Docker TUF root, as well as describing entirely independent policies. For example:
+
+```golang
+// configure policy options
+opts := &policy.PolicyOptions{
+  TufClient:       tufClient,
+  LocalPolicyDir:  "<policy-dir>", // overrides TUF policy for local policy files if set
+  PolicyId:        "<policy-id>", // set to ignore policy mapping and select a policy by id
+}
+
+src, err := oci.ParseImageSpec(image, oci.WithPlatform(platform))
+if err != nil {
+  panic(err)
+}
+// verify attestations
+result, err := attest.Verify(context.Background(), src, opts)
+if err != nil {
+  panic(err)
+}
+```
+
+where `<policy-dir>` is a directory containing a `mapping.yaml` file, and any policy files referenced in the `mapping.yaml`. For example:
+
+```
+├── myimages
+│   ├── data.yaml
+|   ├── keys.yaml
+│   └── policy.rego
+└── mapping.yaml
+```
+
+> [!NOTE]
+>
+> `PolicyId` can also be set to select a policy by ID, completely ignoring the `rules` section of the mapping file.
+
+The rules section of a local `mapping.yaml` can refer to the policies described in the `mapping.yaml` file in the Docker TUF root to specify additional mirrors to which the referenced policy can be applied.
+
+For example, it might be desirable to mirror `docker.io/library` to a local registry for testing:
+
+```yaml
+version: v1
+kind: policy-mapping
+rules:
+  - pattern: "^localhost:5001/(.*)$"
+    rewrite: docker.io/library/$1
+```
+
+The rewritten repository name will match the `docker-official-images` polict in the TUF managed `mapping.yaml`.
+
+> [!WARNING]
+> Local `mapping.yaml` policies take precendence over TUF managed policies, so for example, it's possible to apply a custom policy to `docker.io/library` namespace:
+>
+> ```yaml
+> version: v1
+> kind: policy-mapping
+> policies:
+>   - id: mydoi
+>     description: my doi policy
+>     files:
+>       - path: "mypolicy.rego"
+>
+> rules:
+>   - pattern: "^docker[.]io/library/(.*)$"
+>     policy-id: mydoi
+> ```
+
+# Public Key IDs
+
+When signing attestations, a key-id is generated from the public key and added to envelope.
+This is used at verification time to look up the public key.
+
+To generate a key-id from a public key, use `openssl` as follows:
+
+```shell
+openssl pkey -in <public-key.pem> -pubin -outform DER | openssl dgst -sha256
+```
+
+# Transparency Logging
+
+`attest` supports transparency logging for attestation signatures.
+This serves two purposes:
+
+1. the transparency log is a mechanism to ensure that all attestations are logged in a tamper-evident way, and that the logs are publicly auditable; and
+2. the transparency log is a trusted source of timestamps for attestations, which allows signatures to be verified even if the key used to sign the attestation has expired.
+
+By default, transparency logging is enabled and the logs are stored in the [public-good Rekor](https://docs.sigstore.dev/logging/overview/) instance.
+Another transparency log can be used by creating an implementation of the [tl.TL](https://github.com/docker/attest/blob/781a738b54b9549c1dabfd7ea3f7ea582514ddec/pkg/tlog/tl.go#L57-L62) interface and using [`tl.WithTL`](https://github.com/docker/attest/blob/781a738b54b9549c1dabfd7ea3f7ea582514ddec/pkg/tlog/tl.go#L37) to set in on a context.
+Alternatively, transparency logging can be disabled when signing by using `SkipTL` in the `SigningOptions`, and when verifying by using `skip_tl` in the options to `attest.verify` in the Rego policy.
+
+# Verification Summary Attestation (VSA)
+
+Verification of attestations can be expensive, especially when the attestations are large.
+For example, an SBOM attestation can be several megabytes in size.
+An alternative to consumers verifying the full attestation is to have a trusted entity verify the attestation and publish a [SLSA Verification Summary Attestation](https://slsa.dev/spec/v1.0/verification_summary) (VSA) to the registry.
+The VSA can then be verified by the consumer without needing to verify the full attestation, as long as the consumer trusts the entity that signed the VSA.
+This is useful when the consumer only needs to know that the attestation was verified by a trusted entity, and does not need to know the details of the attestation.
+
+A useful pattern is to have apply a policy to a third-party image at initial ingress, then publish a VSA when publishing the image to an internal registry to attest that the image complies with the policy.
+The VSA can be verified very quickly, for example in a Kubernetes admission controller.
+
+`attest` always generates a [SLSA VSA](https://slsa.dev/spec/v1.0/verification_summary) when verifying attestations on an image.
+The VSA can be signed and published to the registry using the signing functions mentioned in [Signing Attestations](#signing-attestations).
+
+## Example VSA
+
+```json
+{
+  "_type": "https://in-toto.io/Statement/v1",
+  "subject": [
+    {
+      "name": "pkg:docker/example.org/example-image@1.0?platform=linux%2Famd64",
+      "digest": {
+        "sha256": "49f717386e5462e945232569a97a05831cb83bef8c3369be3bb7ea1793686960"
+      }
+    }
+  ],
+  "predicateType": "https://slsa.dev/verification_summary/v1",
+  "predicate": {
+    "verifier": {
+      "id": "https://example.org/internal-verifier"
+    },
+    "timeVerified": "2024-04-19T08:00:00.01Z",
+    "resourceUri": "pkg:docker/example.org/example-image@1.0?platform=linux%2Famd64&digest=sha256%3A49f717386e5462e945232569a97a05831cb83bef8c3369be3bb7ea1793686960",
+    "policy": {
+      "uri": "https://example.org/internal-policy/v1",
+      "downloadLocation": "https://docker.github.io/tuf-staging/targets/docker/d71d6b8f49fcba1295b16f5394dd5863a14e4277eb663d66d8c48e392509afe0.policy.rego",
+      "digest": {
+        "sha256": "d71d6b8f49fcba1295b16f5394dd5863a14e4277eb663d66d8c48e392509afe0"
+      }
+    },
+    "verificationResult": "PASSED",
+    "verifiedLevels": ["SLSA_BUILD_LEVEL_3"]
+  }
+}
+```
+
+# API Reference
+
+Full API reference can be found at [pkg.go.dev/github.com/docker/attest](https://pkg.go.dev/github.com/docker/attest).
+
+# Project Layout
+
+- [pkg/](https://pkg.go.dev/github.com/docker/image-signer-verifier/pkg) => packages that are okay to import for other projects
+- [internal/](https://pkg.go.dev/github.com/docker/image-signer-verifier/pkg) => packages that are only for project internal purposes
+- [scripts/](scripts/) => build scripts
+- [test/](test/) => data for use in tests
+
+# Versioning
+
+`attest` uses [Semantic Versioning](https://semver.org/).
+As such, until `attest` reaches version 1.0.0, breaking changes may be introduced in minor versions.
+
+> Anything MAY change at any time. The public API SHOULD NOT be considered stable.

attestation/README.md

@@ -0,0 +1,4 @@
+## attestations
+This package is for components that deal with the creation, storage, and retrieval of signed attestions using OCI. 
+
+For more generic OCI components see the `oci` package.

attestation/attestation.go

@@ -0,0 +1,470 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"maps"
+	"strings"
+
+	"github.com/docker/attest/oci"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+	"github.com/google/go-containerregistry/pkg/v1/match"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
+	"github.com/google/go-containerregistry/pkg/v1/static"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/secure-systems-lab/go-securesystemslib/dsse"
+)
+
+// NewManifest creates a new attestation manifest from a descriptor.
+func NewManifest(subject *v1.Descriptor) (*Manifest, error) {
+	return &Manifest{
+		OriginalDescriptor: &v1.Descriptor{
+			MediaType: "application/vnd.oci.image.manifest.v1+json",
+		},
+		OriginalLayers:    []*Layer{},
+		SubjectDescriptor: subject,
+	}, nil
+}
+
+// ManifestsFromIndex extracts all attestation manifests from an index.
+func ManifestsFromIndex(index v1.ImageIndex) ([]*Manifest, error) {
+	idx, err := index.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract IndexManifest from ImageIndex: %w", err)
+	}
+	subjects := make(map[string]*v1.Descriptor)
+	for i := range idx.Manifests {
+		subject := &idx.Manifests[i]
+		subjects[subject.Digest.String()] = subject
+	}
+
+	var attestationManifests []*Manifest
+	for i := range idx.Manifests {
+		desc := idx.Manifests[i]
+		if desc.Annotations[DockerReferenceType] == AttestationManifestType {
+			subject := subjects[desc.Annotations[DockerReferenceDigest]]
+			if subject == nil {
+				return nil, fmt.Errorf("failed to find subject for attestation manifest: %w", err)
+			}
+			attestationImage, err := index.Image(desc.Digest)
+			if err != nil {
+				return nil, fmt.Errorf("failed to extract attestation image with digest %s: %w", desc.Digest.String(), err)
+			}
+			attestationLayers, err := layersFromImage(attestationImage)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get attestations from image: %w", err)
+			}
+			attestationManifests = append(attestationManifests,
+				&Manifest{
+					OriginalDescriptor: &desc,
+					SubjectDescriptor:  subject,
+					OriginalLayers:     attestationLayers,
+				})
+		}
+	}
+	return attestationManifests, nil
+}
+
+// LayersFromImage extracts all attestation layers from an image.
+func layersFromImage(image v1.Image) ([]*Layer, error) {
+	layers, err := image.Layers()
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract layers from image: %w", err)
+	}
+	var attestationLayers []*Layer
+	for _, layer := range layers {
+		// parse layer blob as json
+		r, err := layer.Uncompressed()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get layer contents: %w", err)
+		}
+		defer r.Close()
+		mt, err := layer.MediaType()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get layer media type: %w", err)
+		}
+		layerDesc, err := partial.Descriptor(layer)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get descriptor for layer: %w", err)
+		}
+		// copy original annotations
+		ann := maps.Clone(layerDesc.Annotations)
+		// only decode intoto statements
+		var stmt *intoto.Statement
+		if mt == types.MediaType(intoto.PayloadType) {
+			stmt = new(intoto.Statement)
+			err = json.NewDecoder(r).Decode(&stmt)
+			if err != nil {
+				return nil, fmt.Errorf("failed to decode statement layer contents: %w", err)
+			}
+		}
+		attestationLayers = append(attestationLayers, &Layer{Layer: layer, Statement: stmt, Annotations: ann})
+	}
+	return attestationLayers, nil
+}
+
+func (manifest *Manifest) Add(ctx context.Context, signer dsse.SignerVerifier, statement *intoto.Statement, opts *SigningOptions) error {
+	layer, err := createSignedImageLayer(ctx, statement, signer, opts)
+	if err != nil {
+		return fmt.Errorf("failed to create signed layer: %w", err)
+	}
+	manifest.SignedLayers = append(manifest.SignedLayers, layer)
+	return nil
+}
+
+func createSignedImageLayer(ctx context.Context, statement *intoto.Statement, signer dsse.SignerVerifier, opts *SigningOptions) (*Layer, error) {
+	// sign the statement
+	env, err := signInTotoStatement(ctx, statement, signer, opts)
+	if err != nil {
+		return nil, fmt.Errorf("failed to sign statement: %w", err)
+	}
+
+	mediaType, err := DSSEMediaType(statement.PredicateType)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get DSSE media type: %w", err)
+	}
+	data, err := json.Marshal(env)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal envelope: %w", err)
+	}
+	return &Layer{
+		Statement: statement,
+		Annotations: map[string]string{
+			InTotoPredicateType:           statement.PredicateType,
+			InTotoReferenceLifecycleStage: LifecycleStageExperimental,
+		},
+		Layer: static.NewLayer(data, types.MediaType(mediaType)),
+	}, nil
+}
+
+func signInTotoStatement(ctx context.Context, statement *intoto.Statement, signer dsse.SignerVerifier, opts *SigningOptions) (*Envelope, error) {
+	payload, err := json.Marshal(statement)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal statement: %w", err)
+	}
+	env, err := SignDSSE(ctx, payload, signer, opts)
+	if err != nil {
+		return nil, fmt.Errorf("failed to sign statement: %w", err)
+	}
+	return env, nil
+}
+
+func updateImageIndex(
+	idx v1.ImageIndex,
+	manifest *Manifest,
+	options ...func(*ManifestImageOptions) error,
+) (v1.ImageIndex, error) {
+	image, err := manifest.BuildImage(options...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to build image: %w", err)
+	}
+	newDesc, err := partial.Descriptor(image)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get descriptor: %w", err)
+	}
+	newDesc.Platform = &v1.Platform{
+		Architecture: "unknown",
+		OS:           "unknown",
+	}
+	newDesc.MediaType = manifest.OriginalDescriptor.MediaType
+	newDesc.Annotations = manifest.OriginalDescriptor.Annotations
+	idx = mutate.RemoveManifests(idx, match.Digests(manifest.OriginalDescriptor.Digest))
+	idx = mutate.AppendManifests(idx, mutate.IndexAddendum{
+		Add:        image,
+		Descriptor: *newDesc,
+	})
+	return idx, nil
+}
+
+func UpdateIndexImages(idx v1.ImageIndex, manifest []*Manifest, options ...func(*ManifestImageOptions) error) (v1.ImageIndex, error) {
+	var err error
+	for _, m := range manifest {
+		idx, err = updateImageIndex(idx, m, options...)
+		if err != nil {
+			return nil, fmt.Errorf("failed to add image to index: %w", err)
+		}
+	}
+	return idx, nil
+}
+
+func newOptions(options ...func(*ManifestImageOptions) error) (*ManifestImageOptions, error) {
+	opts := &ManifestImageOptions{}
+	for _, opt := range options {
+		err := opt(opts)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return opts, nil
+}
+
+func WithoutSubject(skipSubject bool) func(*ManifestImageOptions) error {
+	return func(r *ManifestImageOptions) error {
+		r.skipSubject = skipSubject
+		return nil
+	}
+}
+
+func WithReplacedLayers(replaceLayers bool) func(*ManifestImageOptions) error {
+	return func(r *ManifestImageOptions) error {
+		r.replaceLayers = replaceLayers
+		return nil
+	}
+}
+
+// build an image with signed attestations, optionally replacing existing layers with signed layers.
+func (manifest *Manifest) BuildImage(options ...func(*ManifestImageOptions) error) (v1.Image, error) {
+	opts, err := newOptions(options...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create options: %w", err)
+	}
+	resultLayers := manifest.SignedLayers
+	for _, existingLayer := range manifest.OriginalLayers {
+		var found bool
+		for _, signedLayer := range manifest.SignedLayers {
+			if existingLayer.Statement == signedLayer.Statement {
+				found = true
+				// copy over original annotations
+				for k, v := range existingLayer.Annotations {
+					signedLayer.Annotations[k] = v
+				}
+				break
+			}
+		}
+		// add existing layers if they've not been signed or we're not replacing them
+		if !found || !opts.replaceLayers {
+			resultLayers = append(resultLayers, existingLayer)
+		}
+	}
+	// so that we attach all attestations to a single attestations image - as per current buildkit
+	opts.laxReferrers = true
+	newImg, err := buildImageFromLayers(resultLayers, manifest.OriginalDescriptor, manifest.SubjectDescriptor, opts)
+	if err != nil {
+		return nil, fmt.Errorf("failed to build image: %w", err)
+	}
+	return newImg, nil
+}
+
+// build an image per attestation (layer) suitable for use as Referrers.
+func (manifest *Manifest) BuildReferringArtifacts() ([]v1.Image, error) {
+	var images []v1.Image
+	for _, layer := range manifest.SignedLayers {
+		opts := &ManifestImageOptions{}
+		newImg, err := buildImageFromLayers([]*Layer{layer}, manifest.OriginalDescriptor, manifest.SubjectDescriptor, opts)
+		if err != nil {
+			return nil, fmt.Errorf("failed to build image: %w", err)
+		}
+		images = append(images, newImg)
+	}
+	return images, nil
+}
+
+// build an image containing only layers provided.
+func buildImageFromLayers(layers []*Layer, manifest *v1.Descriptor, subject *v1.Descriptor, opts *ManifestImageOptions) (v1.Image, error) {
+	newImg := empty.Image
+	var err error
+	if len(layers) == 0 {
+		return nil, fmt.Errorf("no layers supplied to build image")
+	}
+	// NB: if we add the subject before the layers, it does not end up being computed/serialized in the output for some reason
+	// TODO - recreate this bug and push upstream
+	for _, layer := range layers {
+		add := mutate.Addendum{
+			Layer:       layer.Layer,
+			Annotations: layer.Annotations,
+		}
+		newImg, err = mutate.Append(newImg, add)
+		if err != nil {
+			return nil, fmt.Errorf("failed to add layer to image: %w", err)
+		}
+	}
+
+	// this is for attaching attestations to an attestation image in the index
+	if opts.laxReferrers {
+		newImg = mutate.ConfigMediaType(newImg, "application/vnd.oci.image.config.v1+json")
+	} else {
+		dsseMediatType, err := DSSEMediaType(layers[0].Statement.PredicateType)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get DSSE media type: %w", err)
+		}
+		newImg = mutate.ArtifactType(newImg, dsseMediatType)
+		newImg = mutate.ConfigMediaType(newImg, "application/vnd.oci.empty.v1+json")
+	}
+	// we need to set this even when we set the artifact type otherwise things break (even the go-container-registry client)
+	// even though it's allowed to be empty by spec when setting artifact type
+	newImg = mutate.MediaType(newImg, manifest.MediaType)
+
+	// see note above - must be added after the layers!
+	if !opts.skipSubject {
+		subject.Platform = nil
+		ok := false
+		newImg, ok = mutate.Subject(newImg, *subject).(v1.Image)
+		if !ok {
+			return nil, fmt.Errorf("failed to set subject: %w", err)
+		}
+	}
+	if !opts.laxReferrers {
+		// as per https://github.com/opencontainers/image-spec/blob/main/manifest.md#guidance-for-an-empty-descriptor
+		newImg = &oci.EmptyConfigImage{Image: newImg}
+	}
+	return newImg, nil
+}
+
+func ExtractEnvelopes(manifest *Manifest, predicateType string) ([]*EnvelopeReference, error) {
+	var envs []*EnvelopeReference
+	dsseMediaType, err := DSSEMediaType(predicateType)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get DSSE media type for predicate '%s': %w", predicateType, err)
+	}
+	for _, attestationLayer := range manifest.OriginalLayers {
+		mt, err := attestationLayer.Layer.MediaType()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get layer media type: %w", err)
+		}
+		if string(mt) == dsseMediaType {
+			reader, err := attestationLayer.Layer.Uncompressed()
+			if err != nil {
+				return nil, fmt.Errorf("failed to get layer contents: %w", err)
+			}
+			defer reader.Close()
+			env := new(EnvelopeReference)
+			err = json.NewDecoder(reader).Decode(&env)
+			if err != nil {
+				return nil, fmt.Errorf("failed to decode envelope: %w", err)
+			}
+			var uri string
+			if len(manifest.OriginalDescriptor.URLs) > 0 {
+				uri = manifest.OriginalDescriptor.URLs[0]
+			}
+			env.ResourceDescriptor = &ResourceDescriptor{
+				MediaType: string(mt),
+				Digest:    map[string]string{manifest.OriginalDescriptor.Digest.Algorithm: manifest.OriginalDescriptor.Digest.Hex},
+				URI:       uri,
+			}
+			envs = append(envs, env)
+		}
+	}
+
+	return envs, nil
+}
+
+func ExtractStatementsFromIndex(idx v1.ImageIndex, mediaType string) ([]*AnnotatedStatement, error) {
+	mfs2, err := idx.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract IndexManifest from ImageIndex: %w", err)
+	}
+
+	var statements []*AnnotatedStatement
+
+	for i := range mfs2.Manifests {
+		mf := &mfs2.Manifests[i]
+		if mf.Annotations[DockerReferenceType] != "attestation-manifest" {
+			continue
+		}
+
+		attestationImage, err := idx.Image(mf.Digest)
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract attestation image with digest %s: %w", mf.Digest.String(), err)
+		}
+		layers, err := attestationImage.Layers()
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract layers from attestation image: %w", err)
+		}
+
+		for _, layer := range layers {
+			// parse layer blob as json
+			mt, err := layer.MediaType()
+			if err != nil {
+				return nil, fmt.Errorf("failed to get layer media type: %w", err)
+			}
+
+			if string(mt) != mediaType {
+				continue
+			}
+			r, err := layer.Uncompressed()
+			if err != nil {
+				return nil, fmt.Errorf("failed to get layer contents: %w", err)
+			}
+			defer r.Close()
+			inTotoStatement := new(intoto.Statement)
+			var desc *v1.Descriptor
+			if strings.HasSuffix(string(mt), "+dsse") {
+				env := new(Envelope)
+				err = json.NewDecoder(r).Decode(env)
+				if err != nil {
+					return nil, fmt.Errorf("failed to decode env: %w", err)
+				}
+				payload, err := base64.StdEncoding.Strict().DecodeString(env.Payload)
+				if err != nil {
+					return nil, fmt.Errorf("failed to decode payload: %w", err)
+				}
+				err = json.Unmarshal([]byte(payload), inTotoStatement)
+				if err != nil {
+					return nil, fmt.Errorf("failed to decode %s statement: %w", mediaType, err)
+				}
+			} else {
+				desc := new(v1.Descriptor)
+				err = json.NewDecoder(r).Decode(desc)
+				if err != nil {
+					return nil, fmt.Errorf("failed to decode statement: %w", err)
+				}
+			}
+
+			layerDesc, err := partial.Descriptor(layer)
+			if err != nil {
+				return nil, fmt.Errorf("failed to get descriptor for layer: %w", err)
+			}
+			annotations := make(map[string]string)
+			for k, v := range layerDesc.Annotations {
+				annotations[k] = v
+			}
+			statements = append(statements, &AnnotatedStatement{
+				OCIDescriptor:   desc,
+				InTotoStatement: inTotoStatement,
+				Annotations:     annotations,
+			})
+		}
+	}
+	return statements, nil
+}
+
+func ExtractAnnotatedStatements(path string, mediaType string) ([]*AnnotatedStatement, error) {
+	idx, err := layout.ImageIndexFromPath(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load image index: %w", err)
+	}
+
+	idxm, err := idx.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get digest: %w", err)
+	}
+	idxDigest := idxm.Manifests[0].Digest
+
+	mfs, err := idx.ImageIndex(idxDigest)
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract ImageIndex for digest %s: %w", idxDigest.String(), err)
+	}
+	return ExtractStatementsFromIndex(mfs, mediaType)
+}

attestation/attestation_test.go

@@ -0,0 +1,34 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation_test
+
+import (
+	"testing"
+
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/internal/test"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/stretchr/testify/assert"
+)
+
+const ExpectedStatements = 4
+
+func TestExtractAnnotatedStatements(t *testing.T) {
+	statements, err := attestation.ExtractAnnotatedStatements(test.UnsignedTestIndex(".."), intoto.PayloadType)
+	assert.NoError(t, err)
+	assert.Equalf(t, len(statements), ExpectedStatements, "expected %d statement, got %d", ExpectedStatements, len(statements))
+}

attestation/example_attestation_manifest_test.go

@@ -0,0 +1,106 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation_test
+
+import (
+	"context"
+	"time"
+
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/signerverifier"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/common"
+)
+
+func ExampleManifest() {
+	// configure signerverifier
+	// local signer (unsafe for production)
+	signer, err := signerverifier.GenKeyPair()
+	if err != nil {
+		panic(err)
+	}
+	// example using AWS KMS signer
+	// aws_arn := "arn:aws:kms:us-west-2:123456789012:key/12345678-1234-1234-1234-123456789012"
+	// aws_region := "us-west-2"
+	// signer, err := signerverifier.GetAWSSigner(cmd.Context(), aws_arn, aws_region)
+
+	// configure signing options
+	opts := &attestation.SigningOptions{
+		TransparencyLog: nil, // set this to log to a transparency log
+	}
+
+	ref := "docker/image-signer-verifier:latest"
+
+	digest, err := v1.NewHash("sha256:7ae6b41655929ad8e1848064874a98ac3f68884996c79907f6525e3045f75390")
+	if err != nil {
+		panic(err)
+	}
+	desc := &v1.Descriptor{
+		Digest:    digest,
+		Size:      1234,
+		MediaType: "application/vnd.oci.image.manifest.v1+json",
+	}
+
+	// the in-toto statement to be signed
+	statement := &intoto.Statement{
+		StatementHeader: intoto.StatementHeader{
+			PredicateType: attestation.VSAPredicateType,
+			Subject:       []intoto.Subject{{Name: ref, Digest: common.DigestSet{digest.Algorithm: digest.Hex}}},
+			Type:          intoto.StatementInTotoV01,
+		},
+		Predicate: attestation.VSAPredicate{
+			Verifier: attestation.VSAVerifier{
+				ID: "test-verifier",
+			},
+			TimeVerified:       time.Now().UTC().Format(time.RFC3339),
+			ResourceURI:        "some-uri",
+			Policy:             attestation.VSAPolicy{URI: "some-uri"},
+			VerificationResult: "PASSED",
+			VerifiedLevels:     []string{"SLSA_BUILD_LEVEL_1"},
+		},
+	}
+
+	// create a new manifest to hold the attestation
+	manifest, err := attestation.NewManifest(desc)
+	if err != nil {
+		panic(err)
+	}
+
+	// sign and add the attestation to the manifest
+	err = manifest.Add(context.Background(), signer, statement, opts)
+	if err != nil {
+		panic(err)
+	}
+
+	output, err := oci.ParseImageSpecs("docker/image-signer-verifier-referrers:latest")
+	if err != nil {
+		panic(err)
+	}
+
+	// save the manifest to the registry as a referrers artifact
+	artifacts, err := manifest.BuildReferringArtifacts()
+	if err != nil {
+		panic(err)
+	}
+	ctx := context.Background()
+	err = oci.SaveImagesNoTag(ctx, artifacts, output)
+	if err != nil {
+		panic(err)
+	}
+}

attestation/layout.go

@@ -0,0 +1,197 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	containerd "github.com/containerd/containerd/v2/core/images"
+	"github.com/distribution/reference"
+	"github.com/docker/attest/oci"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+// implementation of Resolver that closes over attestations from an oci layout.
+
+var _ Resolver = (*LayoutResolver)(nil)
+
+type LayoutResolver struct {
+	*Manifest
+	*oci.ImageSpec
+}
+
+func NewOCILayoutResolver(src *oci.ImageSpec) (*LayoutResolver, error) {
+	r := &LayoutResolver{
+		ImageSpec: src,
+	}
+	_, err := r.fetchManifest()
+	if err != nil {
+		return nil, err
+	}
+	return r, nil
+}
+
+func (r *LayoutResolver) fetchManifest() (*Manifest, error) {
+	if r.Manifest == nil {
+		m, err := manifestFromOCILayout(r.Identifier, r.ImageSpec.Platform)
+		if err != nil {
+			return nil, err
+		}
+		r.Manifest = m
+	}
+
+	return r.Manifest, nil
+}
+
+func (r *LayoutResolver) Attestations(_ context.Context, predicateType string) ([]*EnvelopeReference, error) {
+	var envs []*EnvelopeReference
+	dsseMediaType, err := DSSEMediaType(predicateType)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get DSSE media type for predicate '%s': %w", predicateType, err)
+	}
+	for _, attestationLayer := range r.Manifest.OriginalLayers {
+		mt, err := attestationLayer.Layer.MediaType()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get layer media type: %w", err)
+		}
+		mts := string(mt)
+		if mts != dsseMediaType {
+			continue
+		}
+		env := new(EnvelopeReference)
+		// parse layer blob as json
+		layer, err := attestationLayer.Layer.Uncompressed()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get layer contents: %w", err)
+		}
+		defer layer.Close()
+		err = json.NewDecoder(layer).Decode(env)
+		if err != nil {
+			return nil, fmt.Errorf("failed to decode envelope: %w", err)
+		}
+		var uri string
+		if len(r.Manifest.OriginalDescriptor.URLs) > 0 {
+			uri = r.Manifest.OriginalDescriptor.URLs[0]
+		}
+		env.ResourceDescriptor = &ResourceDescriptor{
+			MediaType: string(mt),
+			Digest:    map[string]string{r.Manifest.OriginalDescriptor.Digest.Algorithm: r.Manifest.OriginalDescriptor.Digest.Hex},
+			URI:       uri,
+		}
+		envs = append(envs, env)
+	}
+	return envs, nil
+}
+
+func (r *LayoutResolver) ImageName(_ context.Context) (string, error) {
+	return r.SubjectName, nil
+}
+
+func (r *LayoutResolver) ImageDescriptor(_ context.Context) (*v1.Descriptor, error) {
+	return r.SubjectDescriptor, nil
+}
+
+func (r *LayoutResolver) ImagePlatform(_ context.Context) (*v1.Platform, error) {
+	return r.ImageSpec.Platform, nil
+}
+
+func manifestFromOCILayout(path string, platform *v1.Platform) (*Manifest, error) {
+	layoutIndex, err := layout.ImageIndexFromPath(path)
+	if err != nil {
+		return nil, err
+	}
+
+	layoutIndexManifest, err := layoutIndex.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get digest: %w", err)
+	}
+
+	layoutDescriptor := layoutIndexManifest.Manifests[0]
+	layoutDescriptorDigest := layoutDescriptor.Digest
+	subjectName := layoutDescriptor.Annotations[ocispec.AnnotationRefName]
+	if _, err := reference.ParseNamed(subjectName); err != nil {
+		// try the containerd annotation if the org.opencontainers.image.ref.name is not a full name
+		subjectName = layoutDescriptor.Annotations[containerd.AnnotationImageName]
+		if _, err := reference.ParseNamed(subjectName); err != nil {
+			return nil, fmt.Errorf("failed to find subject name in annotations")
+		}
+	}
+
+	// check if digest refers to an image or an index
+	_, err = layoutIndex.Image(layoutDescriptorDigest)
+	if err == nil {
+		return &Manifest{
+			OriginalLayers:     nil,
+			OriginalDescriptor: nil,
+			SubjectName:        subjectName,
+			SubjectDescriptor:  &layoutDescriptor,
+		}, nil
+	}
+
+	subjectIndex, err := layoutIndex.ImageIndex(layoutDescriptorDigest)
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract ImageIndex for digest %s: %w", layoutDescriptorDigest.String(), err)
+	}
+	subjectIndexManifest, err := subjectIndex.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract IndexManifest from ImageIndex: %w", err)
+	}
+	var subjectDescriptor *v1.Descriptor
+	for i := range subjectIndexManifest.Manifests {
+		manifest := &subjectIndexManifest.Manifests[i]
+		if manifest.Platform != nil {
+			if manifest.Platform.Equals(*platform) {
+				subjectDescriptor = manifest
+				break
+			}
+		}
+	}
+	if subjectDescriptor == nil {
+		return nil, fmt.Errorf("platform not found in index")
+	}
+	for i := range subjectIndexManifest.Manifests {
+		mf := &subjectIndexManifest.Manifests[i]
+		if mf.Annotations[DockerReferenceType] != AttestationManifestType {
+			continue
+		}
+
+		if mf.Annotations[DockerReferenceDigest] != subjectDescriptor.Digest.String() {
+			continue
+		}
+
+		attestationImage, err := subjectIndex.Image(mf.Digest)
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract attestation image with digest %s: %w", mf.Digest.String(), err)
+		}
+		layers, err := layersFromImage(attestationImage)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get attestations from image: %w", err)
+		}
+		attest := &Manifest{
+			OriginalLayers:     layers,
+			OriginalDescriptor: mf,
+			SubjectName:        subjectName,
+			SubjectDescriptor:  subjectDescriptor,
+		}
+		return attest, nil
+	}
+	return nil, fmt.Errorf("attestation manifest not found")
+}

attestation/layout_test.go

@@ -0,0 +1,123 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation_test
+
+import (
+	"context"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/docker/attest"
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/policy"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAttestationFromOCILayout(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	outputLayout := test.CreateTempDir(t, "", "attest-oci-layout")
+
+	invalidPlatform := &v1.Platform{
+		Architecture: "invalid",
+		OS:           "invalid",
+	}
+
+	opts := &attestation.SigningOptions{}
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+	require.NoError(t, err)
+	signedManifests, err := attest.SignStatements(ctx, attIdx.Index, signer, opts)
+	require.NoError(t, err)
+	signedIndex := attIdx.Index
+	signedIndex, err = attestation.UpdateIndexImages(signedIndex, signedManifests)
+	require.NoError(t, err)
+	spec, err := oci.ParseImageSpec(oci.LocalPrefix + outputLayout)
+	require.NoError(t, err)
+	err = oci.SaveIndex(ctx, []*oci.ImageSpec{spec}, signedIndex, "docker.io/library/test-image:test")
+	require.NoError(t, err)
+
+	testCases := []struct {
+		name     string
+		platform *v1.Platform
+		errorStr string
+	}{
+		{name: "nominal", platform: spec.Platform},
+		{name: "invalid platform", platform: invalidPlatform, errorStr: "platform not found in index"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			spec := &oci.ImageSpec{
+				Type:       oci.OCI,
+				Identifier: outputLayout,
+				Platform:   tc.platform,
+			}
+			resolver, err := policy.CreateImageDetailsResolver(spec)
+			if tc.errorStr != "" {
+				require.Error(t, err)
+				assert.Contains(t, err.Error(), tc.errorStr)
+				return
+			}
+			require.NoError(t, err)
+			desc, err := resolver.ImageDescriptor(ctx)
+			require.NoError(t, err)
+			digest := desc.Digest.String()
+			assert.True(t, strings.Contains(digest, "sha256:"))
+		})
+	}
+}
+
+func TestSubjectNameAnnotations(t *testing.T) {
+	testCases := []struct {
+		name          string
+		ociLayoutPath string
+		errorStr      string
+	}{
+		{name: "oci annotation", ociLayoutPath: test.UnsignedTestIndex("..")},
+		{name: "containerd annotation", ociLayoutPath: filepath.Join("..", "test", "testdata", "containerd-subject-layout")},
+		{name: "missing subject name", ociLayoutPath: filepath.Join("..", "test", "testdata", "missing-subject-layout"), errorStr: "failed to find subject name in annotations"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			spec, err := oci.ParseImageSpec(oci.LocalPrefix+tc.ociLayoutPath, oci.WithPlatform("linux/arm64"))
+			require.NoError(t, err)
+			_, err = policy.CreateImageDetailsResolver(spec)
+			if tc.errorStr != "" {
+				require.Error(t, err)
+				assert.Contains(t, err.Error(), tc.errorStr)
+				return
+			}
+			require.NoError(t, err)
+		})
+	}
+}
+
+func TestImageDetailsFromImageLayout(t *testing.T) {
+	spec, err := oci.ParseImageSpec(oci.LocalPrefix+test.UnsignedTestImage(".."), oci.WithPlatform("linux/arm64"))
+	require.NoError(t, err)
+	resolver, err := policy.CreateImageDetailsResolver(spec)
+	require.NoError(t, err)
+	desc, err := resolver.ImageDescriptor(context.Background())
+	require.NoError(t, err)
+	digest := desc.Digest.String()
+	assert.Equal(t, "sha256:7ae6b41655929ad8e1848064874a98ac3f68884996c79907f6525e3045f75390", digest)
+}

attestation/mock.go

@@ -0,0 +1,86 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/oci"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+)
+
+// ensure MockResolver implements Resolver.
+var _ oci.ImageDetailsResolver = MockResolver{}
+
+type MockResolver struct {
+	Envs         []*EnvelopeReference
+	Image        string
+	PlatformFn   func() (*v1.Platform, error)
+	DescriptorFn func() (*v1.Descriptor, error)
+	ImangeNameFn func() (string, error)
+}
+
+func (r MockResolver) Attestations(_ context.Context, _ string) ([]*EnvelopeReference, error) {
+	return r.Envs, nil
+}
+
+func (r MockResolver) ImageName(_ context.Context) (string, error) {
+	if r.Image != "" {
+		return r.Image, nil
+	}
+	if r.ImangeNameFn != nil {
+		return r.ImangeNameFn()
+	}
+	return "library/alpine:latest", nil
+}
+
+func (r MockResolver) ImageDescriptor(_ context.Context) (*v1.Descriptor, error) {
+	if r.DescriptorFn != nil {
+		return r.DescriptorFn()
+	}
+	digest, err := v1.NewHash(test.UnsignedLinuxAMD64ImageDigest)
+	if err != nil {
+		return nil, err
+	}
+	return &v1.Descriptor{
+		Digest:    digest,
+		Size:      1234,
+		MediaType: "application/vnd.oci.image.manifest.v1+json",
+	}, nil
+}
+
+func (r MockResolver) ImagePlatform(_ context.Context) (*v1.Platform, error) {
+	if r.PlatformFn != nil {
+		return r.PlatformFn()
+	}
+	return oci.ParsePlatform("linux/amd64")
+}
+
+type MockRegistryResolver struct {
+	Subject      *v1.Descriptor
+	ImageNameStr string
+	*MockResolver
+}
+
+func (r *MockRegistryResolver) ImageDescriptor(_ context.Context) (*v1.Descriptor, error) {
+	return r.Subject, nil
+}
+
+func (r *MockRegistryResolver) ImageName(_ context.Context) (string, error) {
+	return r.ImageNameStr, nil
+}

attestation/referrers.go

@@ -0,0 +1,142 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/docker/attest/oci"
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+// ensure ReferrersResolver implements Resolver.
+var _ Resolver = &ReferrersResolver{}
+
+type ReferrersResolver struct {
+	referrersRepo string
+	oci.ImageDetailsResolver
+}
+
+func NewReferrersResolver(src oci.ImageDetailsResolver, options ...func(*ReferrersResolver) error) (*ReferrersResolver, error) {
+	res := &ReferrersResolver{
+		ImageDetailsResolver: src,
+	}
+	for _, opt := range options {
+		err := opt(res)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return res, nil
+}
+
+func WithReferrersRepo(repo string) func(*ReferrersResolver) error {
+	return func(r *ReferrersResolver) error {
+		r.referrersRepo = repo
+		return nil
+	}
+}
+
+func (r *ReferrersResolver) resolveAttestations(ctx context.Context, predicateType string) ([]*Manifest, error) {
+	dsseMediaType, err := DSSEMediaType(predicateType)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get DSSE media type for predicate '%s': %w", predicateType, err)
+	}
+	imageName, err := r.ImageName(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get image name: %w", err)
+	}
+	subjectRef, err := name.ParseReference(imageName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse reference: %w", err)
+	}
+	desc, err := r.ImageDescriptor(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get descriptor: %w", err)
+	}
+	subjectDigest := desc.Digest.String()
+	var referrersSubjectRef name.Digest
+	if r.referrersRepo != "" {
+		referrersSubjectRef, err = name.NewDigest(fmt.Sprintf("%s@%s", strings.TrimPrefix(r.referrersRepo, oci.RegistryPrefix), subjectDigest))
+		if err != nil {
+			return nil, fmt.Errorf("failed to create referrers reference: %w", err)
+		}
+	} else {
+		referrersSubjectRef = subjectRef.Context().Digest(subjectDigest)
+	}
+	options := oci.WithOptions(ctx, nil)
+	options = append(options, remote.WithFilter("artifactType", dsseMediaType))
+	referrersIndex, err := remote.Referrers(referrersSubjectRef, options...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get referrers: %w", err)
+	}
+	referrersIndexManifest, err := referrersIndex.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get index manifest: %w", err)
+	}
+	aManifests := make([]*Manifest, 0)
+	for i := range referrersIndexManifest.Manifests {
+		m := referrersIndexManifest.Manifests[i]
+		remoteRef := referrersSubjectRef.Context().Digest(m.Digest.String())
+		options = oci.WithOptions(ctx, nil)
+		attestationImage, err := remote.Image(remoteRef, options...)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get referred image: %w", err)
+		}
+		layers, err := layersFromImage(attestationImage)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get attestations from image: %w", err)
+		}
+		if len(layers) != 1 {
+			return nil, fmt.Errorf("expected exactly one layer, got %d", len(layers))
+		}
+		mt, err := layers[0].Layer.MediaType()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get layer media type: %w", err)
+		}
+		if string(mt) != dsseMediaType {
+			return nil, fmt.Errorf("expected layer media type %s, got %s", dsseMediaType, mt)
+		}
+		attest := &Manifest{
+			SubjectName:        imageName,
+			OriginalLayers:     layers,
+			OriginalDescriptor: &m,
+			SubjectDescriptor:  desc,
+		}
+		aManifests = append(aManifests, attest)
+	}
+	return aManifests, nil
+}
+
+func (r *ReferrersResolver) Attestations(ctx context.Context, predicateType string) ([]*EnvelopeReference, error) {
+	manifests, err := r.resolveAttestations(ctx, predicateType)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve attestations: %w", err)
+	}
+	var envs []*EnvelopeReference
+	for _, attest := range manifests {
+		es, err := ExtractEnvelopes(attest, predicateType)
+		if err != nil {
+			return nil, fmt.Errorf("failed to extract envelopes: %w", err)
+		}
+		envs = append(envs, es...)
+	}
+	return envs, nil
+}

attestation/referrers_test.go

@@ -0,0 +1,337 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation_test
+
+import (
+	"fmt"
+	"net/http/httptest"
+	"net/url"
+	"path/filepath"
+	"testing"
+
+	"github.com/docker/attest"
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/mapping"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/policy"
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/google/go-containerregistry/pkg/registry"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var (
+	NoProvenanceImage   = filepath.Join("..", "test", "testdata", "no-provenance-image")
+	PassPolicyDir       = filepath.Join("..", "test", "testdata", "local-policy-pass")
+	LocalPolicy         = filepath.Join("..", "test", "testdata", "local-policy")
+	LocalPolicyAttached = filepath.Join("..", "test", "testdata", "local-policy-attached")
+	PassNoTLPolicyDir   = filepath.Join("..", "test", "testdata", "local-policy-no-tl")
+	FailPolicyDir       = filepath.Join("..", "test", "testdata", "local-policy-fail")
+	TestTempDir         = "attest-sign-test"
+)
+
+func TestAttestationReferenceTypes(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	platforms := []string{"linux/amd64", "linux/arm64"}
+	for _, tc := range []struct {
+		name              string
+		server            *httptest.Server
+		referrersServer   *httptest.Server
+		useDigest         bool
+		referrersRepo     string
+		attestationSource mapping.AttestationStyle
+		expectFailure     bool
+	}{
+		{
+			name:   "referrers support, defaults",
+			server: test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+		},
+		{
+			name:      "use digest",
+			server:    test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+			useDigest: true,
+		},
+		{
+			name:              "attached attestations, referrers repo (mismatched args)",
+			server:            test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+			expectFailure:     true, // mismatched args
+			attestationSource: mapping.AttestationStyleAttached,
+			referrersRepo:     "referrers",
+		},
+		{
+			name:              "referrers attestations, referrers repo (no policy)",
+			server:            test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+			expectFailure:     true, // no policy
+			attestationSource: mapping.AttestationStyleReferrers,
+			referrersRepo:     "referrers",
+		},
+		{
+			name:              "referrers attestations",
+			server:            test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+			attestationSource: mapping.AttestationStyleReferrers,
+		},
+		{
+			name:   "referrers attestations, no referrers support on server",
+			server: test.NewLocalRegistry(ctx, registry.WithReferrersSupport(false)),
+
+			attestationSource: mapping.AttestationStyleReferrers,
+			referrersServer:   test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			s := tc.server
+			defer s.Close()
+
+			if tc.referrersServer != nil {
+				defer tc.referrersServer.Close()
+			}
+			u, err := url.Parse(s.URL)
+			require.NoError(t, err)
+
+			opts := &attestation.SigningOptions{}
+			attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+			require.NoError(t, err)
+
+			indexName := fmt.Sprintf("%s/repo:root", u.Host)
+			require.NoError(t, err)
+
+			outputRepo := indexName
+			if tc.referrersServer != nil {
+				ru, err := url.Parse(s.URL)
+				require.NoError(t, err)
+				tc.referrersRepo = fmt.Sprintf("%s/referrers", ru.Host)
+				outputRepo = tc.referrersRepo
+			}
+			// sign all the statements in the index
+			signedManifests, err := attest.SignStatements(ctx, attIdx.Index, signer, opts)
+			require.NoError(t, err)
+
+			// push subject image so that it can be resolved
+			require.NoError(t, err)
+			err = oci.PushIndexToRegistry(ctx, attIdx.Index, indexName)
+			require.NoError(t, err)
+
+			// upload referrers
+			output, err := oci.ParseImageSpec(outputRepo)
+			require.NoError(t, err)
+			for _, attIdx := range signedManifests {
+				images, err := attIdx.BuildReferringArtifacts()
+				require.NoError(t, err)
+				err = oci.SaveImagesNoTag(ctx, images, []*oci.ImageSpec{output})
+				require.NoError(t, err)
+			}
+
+			for _, platform := range platforms {
+				// can eval policy in the normal way
+				ref := indexName
+				if tc.useDigest {
+					options := oci.WithOptions(ctx, nil)
+					subjectRef, err := name.ParseReference(indexName)
+					require.NoError(t, err)
+					desc, err := remote.Index(subjectRef, options...)
+					require.NoError(t, err)
+					idxDigest, err := desc.Digest()
+					require.NoError(t, err)
+					ref = fmt.Sprintf("%s/repo@%s", u.Host, idxDigest.String())
+				}
+
+				policyOpts := &policy.Options{
+					LocalPolicyDir: LocalPolicy,
+					DisableTUF:     true,
+				}
+
+				if tc.referrersRepo != "" {
+					policyOpts.ReferrersRepo = tc.referrersRepo
+				}
+
+				if tc.attestationSource != "" {
+					policyOpts.AttestationStyle = tc.attestationSource
+				}
+				src, err := oci.ParseImageSpec(ref, oci.WithPlatform(platform))
+				require.NoError(t, err)
+				results, err := attest.Verify(ctx, src, policyOpts)
+				if tc.expectFailure {
+					require.Error(t, err)
+					continue
+				}
+				require.NoError(t, err)
+				assert.Equal(t, attest.OutcomeSuccess, results.Outcome)
+
+				if tc.useDigest {
+					p, err := oci.ParsePlatform(platform)
+					require.NoError(t, err)
+					options := oci.WithOptions(ctx, p)
+					subjectRef, err := name.ParseReference(indexName)
+					require.NoError(t, err)
+					desc, err := remote.Image(subjectRef, options...)
+					require.NoError(t, err)
+					subjectDigest, err := desc.Digest()
+					require.NoError(t, err)
+					ref = fmt.Sprintf("%s/repo@%s", u.Host, subjectDigest.String())
+				}
+				src, err = oci.ParseImageSpec(ref, oci.WithPlatform(platform))
+				require.NoError(t, err)
+				results, err = attest.Verify(ctx, src, policyOpts)
+				require.NoError(t, err)
+				assert.Equal(t, attest.OutcomeSuccess, results.Outcome)
+			}
+		})
+	}
+}
+
+func TestReferencesInDifferentRepo(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	repoName := "repo"
+	for _, tc := range []struct {
+		name      string
+		server    *httptest.Server
+		refServer *httptest.Server
+	}{
+		{
+			name:      "referrers support",
+			server:    test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+			refServer: test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+		},
+		{
+			name:      "no referrers support",
+			server:    test.NewLocalRegistry(ctx, registry.WithReferrersSupport(false)),
+			refServer: test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true)),
+		},
+	} {
+		server := tc.server
+		defer server.Close()
+		serverURL, err := url.Parse(server.URL)
+		require.NoError(t, err)
+
+		refServer := tc.refServer
+		defer refServer.Close()
+		refServerURL, err := url.Parse(refServer.URL)
+		require.NoError(t, err)
+
+		opts := &attestation.SigningOptions{}
+		attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+		require.NoError(t, err)
+
+		indexName := fmt.Sprintf("%s/%s:latest", serverURL.Host, repoName)
+		err = oci.PushIndexToRegistry(ctx, attIdx.Index, indexName)
+		require.NoError(t, err)
+
+		signedManifests, err := attest.SignStatements(ctx, attIdx.Index, signer, opts)
+		require.NoError(t, err)
+
+		// push signed attestation image to the ref server
+		for _, signedManifest := range signedManifests {
+			// push references using subject-digest.att convention
+			image, err := signedManifest.BuildImage()
+			require.NoError(t, err)
+			err = oci.PushImageToRegistry(ctx, image, fmt.Sprintf("%s/%s:tag-does-not-matter", refServerURL.Host, repoName))
+			require.NoError(t, err)
+
+			refServer := tc.refServer
+			defer refServer.Close()
+			refServerURL, err := url.Parse(refServer.URL)
+			require.NoError(t, err)
+
+			opts := &attestation.SigningOptions{}
+			attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+			require.NoError(t, err)
+
+			indexName := fmt.Sprintf("%s/%s:latest", serverURL.Host, repoName)
+			err = oci.PushIndexToRegistry(ctx, attIdx.Index, indexName)
+			require.NoError(t, err)
+
+			signedManifests, err := attest.SignStatements(ctx, attIdx.Index, signer, opts)
+			require.NoError(t, err)
+
+			// push signed attestation image to the ref server
+			for _, mf := range signedManifests {
+				// push references using subject-digest.att convention
+				imgs, err := mf.BuildReferringArtifacts()
+				require.NoError(t, err)
+				for _, img := range imgs {
+					err = oci.PushImageToRegistry(ctx, img, fmt.Sprintf("%s/%s:tag-does-not-matter", refServerURL.Host, repoName))
+					require.NoError(t, err)
+				}
+			}
+			mfs2, err := attIdx.Index.IndexManifest()
+			require.NoError(t, err)
+			for _, mf := range mfs2.Manifests {
+				// skip signed/unsigned attestations
+				if mf.Annotations[attestation.DockerReferenceType] == attestation.AttestationManifestType {
+					continue
+				}
+				// can evaluate policy using referrers in a different repo
+				referencedImage := fmt.Sprintf("%s@%s", indexName, mf.Digest.String())
+				policyOpts := &policy.Options{
+					LocalPolicyDir: PassPolicyDir,
+					DisableTUF:     true,
+				}
+				src, err := oci.ParseImageSpec(referencedImage)
+				require.NoError(t, err)
+				results, err := attest.Verify(ctx, src, policyOpts)
+				require.NoError(t, err)
+				assert.Equal(t, attest.OutcomeSuccess, results.Outcome)
+			}
+		}
+	}
+}
+
+func TestCorrectArtifactTypeInTagFallback(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	regServer := test.NewLocalRegistry(ctx, registry.WithReferrersSupport(false))
+	defer regServer.Close()
+	serverURL, err := url.Parse(regServer.URL)
+	require.NoError(t, err)
+
+	repoName := "repo"
+
+	opts := &attestation.SigningOptions{}
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+	require.NoError(t, err)
+
+	indexName := fmt.Sprintf("%s/%s:latest", serverURL.Host, repoName)
+	err = oci.PushIndexToRegistry(ctx, attIdx.Index, indexName)
+	require.NoError(t, err)
+
+	signedManifests, err := attest.SignStatements(ctx, attIdx.Index, signer, opts)
+	require.NoError(t, err)
+
+	// this should create and maintain an index of referrers
+	for _, mf := range signedManifests {
+		imgs, err := mf.BuildReferringArtifacts()
+		require.NoError(t, err)
+		for _, img := range imgs {
+			err = oci.PushImageToRegistry(ctx, img, fmt.Sprintf("%s/%s:tag-does-not-matter", serverURL.Host, repoName))
+			require.NoError(t, err)
+			mf, err := img.Manifest()
+			require.NoError(t, err)
+			subject := mf.Subject
+			subjectRef, err := name.ParseReference(fmt.Sprintf("%s/%s:sha256-%s", serverURL.Host, repoName, subject.Digest.Hex))
+			require.NoError(t, err)
+			idx, err := remote.Index(subjectRef, oci.WithOptions(ctx, nil)...)
+			require.NoError(t, err)
+			imf, err := idx.IndexManifest()
+			require.NoError(t, err)
+			for _, m := range imf.Manifests {
+				assert.Contains(t, m.ArtifactType, "application/vnd.in-toto")
+				assert.Contains(t, m.ArtifactType, "+dsse")
+			}
+		}
+	}
+}

attestation/registry.go

@@ -0,0 +1,120 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/docker/attest/oci"
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+// ensure RegistryResolver implements Resolver.
+var _ Resolver = &RegistryResolver{}
+
+type RegistryResolver struct {
+	*oci.RegistryImageDetailsResolver
+	*Manifest
+}
+
+func NewRegistryResolver(src *oci.RegistryImageDetailsResolver) (*RegistryResolver, error) {
+	return &RegistryResolver{
+		RegistryImageDetailsResolver: src,
+	}, nil
+}
+
+func (r *RegistryResolver) Attestations(ctx context.Context, predicateType string) ([]*EnvelopeReference, error) {
+	if r.Manifest == nil {
+		attest, err := FetchManifest(ctx, r.Identifier, r.ImageSpec.Platform)
+		if err != nil {
+			return nil, err
+		}
+		r.Manifest = attest
+	}
+	return ExtractEnvelopes(r.Manifest, predicateType)
+}
+
+func attestationDigestForImage(ix *v1.IndexManifest, imageDigest string, attestType string) (string, error) {
+	for i := range ix.Manifests {
+		m := &ix.Manifests[i]
+		if v, ok := m.Annotations[DockerReferenceType]; ok && v == attestType {
+			if d, ok := m.Annotations[DockerReferenceDigest]; ok && d == imageDigest {
+				return m.Digest.String(), nil
+			}
+		}
+	}
+	return "", fmt.Errorf("no attestation found for image %s", imageDigest)
+}
+
+func FetchManifest(ctx context.Context, image string, platform *v1.Platform) (*Manifest, error) {
+	// we want to get to the image index, so ignoring platform for now
+	options := oci.WithOptions(ctx, nil)
+	ref, err := name.ParseReference(image)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse reference: %w", err)
+	}
+	index, err := remote.Index(ref, options...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get index: %w", err)
+	}
+	indexManifest, err := index.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get index manifest: %w", err)
+	}
+	subjectDescriptor, err := oci.ImageDescriptor(indexManifest, platform)
+	if err != nil {
+		return nil, fmt.Errorf("failed to obtain image for platform: %w", err)
+	}
+
+	digest := subjectDescriptor.Digest.String()
+	ref, err = name.ParseReference(fmt.Sprintf("%s@%s", ref.Context().Name(), digest))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse attestation reference: %w", err)
+	}
+
+	attestationDigest, err := attestationDigestForImage(indexManifest, digest, "attestation-manifest")
+	if err != nil {
+		return nil, fmt.Errorf("failed to obtain attestation for image: %w", err)
+	}
+	ref, err = name.ParseReference(fmt.Sprintf("%s@%s", ref.Context().Name(), attestationDigest))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse attestation reference: %w", err)
+	}
+	remoteDescriptor, err := remote.Get(ref, options...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get attestation: %w", err)
+	}
+	attestationImage, err := remoteDescriptor.Image()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get attestation image: %w", err)
+	}
+
+	layers, err := layersFromImage(attestationImage)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get attestations from image: %w", err)
+	}
+	attest := &Manifest{
+		OriginalLayers:     layers,
+		OriginalDescriptor: &remoteDescriptor.Descriptor,
+		SubjectName:        image,
+		SubjectDescriptor:  subjectDescriptor,
+	}
+	return attest, nil
+}

attestation/registry_test.go

@@ -0,0 +1,75 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation_test
+
+import (
+	"fmt"
+	"net/url"
+	"strings"
+	"testing"
+
+	"github.com/docker/attest"
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/policy"
+	"github.com/google/go-containerregistry/pkg/registry"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRegistry(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	regServer := test.NewLocalRegistry(ctx, registry.WithReferrersSupport(false))
+	defer regServer.Close()
+	u, err := url.Parse(regServer.URL)
+	require.NoError(t, err)
+
+	opts := &attestation.SigningOptions{}
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+	require.NoError(t, err)
+	signedManifests, err := attest.SignStatements(ctx, attIdx.Index, signer, opts)
+	require.NoError(t, err)
+	signedIndex := attIdx.Index
+	signedIndex, err = attestation.UpdateIndexImages(signedIndex, signedManifests)
+	require.NoError(t, err)
+
+	indexName := fmt.Sprintf("%s/repo:root", u.Host)
+	require.NoError(t, err)
+	err = oci.PushIndexToRegistry(ctx, signedIndex, indexName)
+	require.NoError(t, err)
+
+	spec, err := oci.ParseImageSpec(indexName)
+	require.NoError(t, err)
+
+	resolver, err := policy.CreateImageDetailsResolver(spec)
+	require.NoError(t, err)
+	desc, err := resolver.ImageDescriptor(ctx)
+	require.NoError(t, err)
+	digest := desc.Digest.String()
+	assert.True(t, strings.Contains(digest, "sha256:"))
+
+	// resolver also works with platform specific digest
+	spec, err = oci.ParseImageSpec(fmt.Sprintf("%s@%s", indexName, digest))
+	require.NoError(t, err)
+
+	resolver, err = policy.CreateImageDetailsResolver(spec)
+	require.NoError(t, err)
+	desc, err = resolver.ImageDescriptor(ctx)
+	require.NoError(t, err)
+	assert.Equal(t, desc.Digest.String(), digest)
+}

attestation/resolver.go

@@ -0,0 +1,28 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+
+	"github.com/docker/attest/oci"
+)
+
+type Resolver interface {
+	oci.ImageDetailsResolver
+	Attestations(ctx context.Context, mediaType string) ([]*EnvelopeReference, error)
+}

attestation/sign.go

@@ -0,0 +1,87 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/docker/attest/internal/util"
+	"github.com/docker/attest/tlog"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/secure-systems-lab/go-securesystemslib/dsse"
+)
+
+// SignDSSE signs a payload with a given signer and uploads the signature to the transparency log.
+func SignDSSE(ctx context.Context, payload []byte, signer dsse.SignerVerifier, opts *SigningOptions) (*Envelope, error) {
+	payloadType := intoto.PayloadType
+	env := new(Envelope)
+	env.Payload = base64Encoding.EncodeToString(payload)
+	env.PayloadType = payloadType
+	encPayload := dsse.PAE(payloadType, payload)
+
+	// statement message digest
+	hash := util.SHA256(encPayload)
+
+	// sign message digest
+	sig, err := signer.Sign(ctx, hash)
+	if err != nil {
+		return nil, fmt.Errorf("error signing attestation: %w", err)
+	}
+
+	// get Key ID from signer
+	keyID, err := signer.KeyID()
+	if err != nil {
+		return nil, fmt.Errorf("error getting public key ID: %w", err)
+	}
+
+	dsseSig := &Signature{
+		KeyID: keyID,
+		Sig:   base64Encoding.EncodeToString(sig),
+	}
+	if opts.TransparencyLog != nil {
+		ext, err := logSignature(ctx, opts.TransparencyLog, sig, encPayload, signer)
+		if err != nil {
+			return nil, fmt.Errorf("failed to log signature: %w", err)
+		}
+		dsseSig.Extension = ext
+	}
+	// add signature to dsse envelope
+	env.Signatures = []*Signature{dsseSig}
+
+	return env, nil
+}
+
+// returns a new envelope with the transparency log entry added to the signature extension.
+func logSignature(ctx context.Context, t tlog.TransparencyLog, sig []byte, encPayload []byte, signer dsse.SignerVerifier) (*Extension, error) {
+	// get Key ID from signer
+	keyID, err := signer.KeyID()
+	if err != nil {
+		return nil, fmt.Errorf("error getting public key ID: %w", err)
+	}
+	entry, err := t.UploadEntry(ctx, keyID, encPayload, sig, signer)
+	if err != nil {
+		return nil, fmt.Errorf("error uploading TL entry: %w", err)
+	}
+
+	return &Extension{
+		Kind: DockerDSSEExtKind,
+		Ext: &DockerDSSEExtension{
+			TL: entry,
+		},
+	}, nil
+}

attestation/sign_test.go

@@ -0,0 +1,329 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation_test
+
+import (
+	"context"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"encoding/json"
+	"fmt"
+	"net/url"
+	"testing"
+	"time"
+
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/signerverifier"
+	"github.com/docker/attest/tlog"
+	"github.com/google/go-containerregistry/pkg/registry"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/static"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSignVerifyAttestation(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	stmt := &intoto.Statement{
+		StatementHeader: intoto.StatementHeader{
+			Type:          intoto.StatementInTotoV01,
+			PredicateType: intoto.PredicateSPDX,
+		},
+		Predicate: "test",
+	}
+
+	payload, err := json.Marshal(stmt)
+	require.NoError(t, err)
+	tl := tlog.GetMockTL()
+	opts := &attestation.SigningOptions{
+		TransparencyLog: tl,
+	}
+	env, err := attestation.SignDSSE(ctx, payload, signer, opts)
+	require.NoError(t, err)
+
+	// marshal envelope to json to test for bugs when marshaling envelope data
+	serializedEnv, err := json.Marshal(env)
+	require.NoError(t, err)
+	deserializedEnv := new(attestation.Envelope)
+	err = json.Unmarshal(serializedEnv, deserializedEnv)
+	require.NoError(t, err)
+
+	// signer.Public() calls AWS API when using AWS signer, use attestation.GetPublicVerificationKey() to get key from TUF repo
+	// signer.Public() used here for test purposes
+	ecPub, ok := signer.Public().(*ecdsa.PublicKey)
+	assert.True(t, ok)
+	pem, err := signerverifier.ConvertToPEM(ecPub)
+	assert.NoError(t, err)
+	keyID, err := signerverifier.KeyID(ecPub)
+	assert.NoError(t, err)
+
+	badKeyPriv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	require.NoError(t, err)
+	badKey := &badKeyPriv.PublicKey
+	badPEM, err := signerverifier.ConvertToPEM(badKey)
+	require.NoError(t, err)
+
+	testCases := []struct {
+		name          string
+		keyID         string
+		pem           []byte
+		distrust      bool
+		from          time.Time
+		to            *time.Time
+		status        string
+		expectedError string
+	}{
+		{
+			name:          "all OK",
+			keyID:         keyID,
+			pem:           pem,
+			distrust:      false,
+			from:          time.Time{},
+			to:            nil,
+			status:        "active",
+			expectedError: "",
+		},
+		{
+			name:          "key not found",
+			keyID:         "someotherkey",
+			pem:           pem,
+			distrust:      false,
+			from:          time.Time{},
+			to:            nil,
+			status:        "active",
+			expectedError: fmt.Sprintf("key not found: %s", keyID),
+		},
+		{
+			name:          "key distrusted",
+			keyID:         keyID,
+			pem:           pem,
+			distrust:      true,
+			from:          time.Time{},
+			to:            nil,
+			status:        "active",
+			expectedError: "distrusted",
+		},
+		{
+			name:          "key not yet valid",
+			keyID:         keyID,
+			pem:           pem,
+			distrust:      false,
+			from:          time.Now().Add(time.Hour),
+			to:            nil,
+			status:        "active",
+			expectedError: "not yet valid",
+		},
+		{
+			name:          "key already revoked",
+			keyID:         keyID,
+			pem:           pem,
+			distrust:      false,
+			from:          time.Time{},
+			to:            new(time.Time),
+			status:        "revoked",
+			expectedError: "already revoked",
+		},
+		{
+			name:          "bad key",
+			keyID:         keyID,
+			pem:           badPEM,
+			distrust:      false,
+			from:          time.Time{},
+			to:            nil,
+			status:        "active",
+			expectedError: "signature is not valid",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			keyMeta := &attestation.KeyMetadata{
+				ID:       tc.keyID,
+				PEM:      string(tc.pem),
+				Distrust: tc.distrust,
+				From:     tc.from,
+				To:       tc.to,
+				Status:   tc.status,
+			}
+			opts := &attestation.VerifyOptions{
+				Keys: attestation.Keys{keyMeta},
+			}
+			getTL := func(_ context.Context, opts *attestation.VerifyOptions) (tlog.TransparencyLog, error) {
+				if opts.SkipTL {
+					return nil, nil
+				}
+				return tl, nil
+			}
+			verifier, err := attestation.NewVerfier(attestation.WithLogVerifierFactory(getTL))
+			require.NoError(t, err)
+			_, err = attestation.VerifyDSSE(ctx, verifier, deserializedEnv, opts)
+			if tc.expectedError != "" {
+				require.Error(t, err)
+				assert.Contains(t, err.Error(), tc.expectedError)
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestAddSignedLayerAnnotations(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	testCases := []struct {
+		name    string
+		replace bool
+	}{
+		{"replaced", true},
+		{"not replaced", false},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			data := []byte("signed")
+			testLayer := static.NewLayer(data, types.MediaType(intoto.PayloadType))
+			mediaType := types.OCIManifestSchema1
+			opts := &attestation.SigningOptions{}
+			originalLayer := &attestation.Layer{
+				Layer: testLayer,
+				Statement: &intoto.Statement{
+					StatementHeader: intoto.StatementHeader{
+						PredicateType: attestation.VSAPredicateType,
+					},
+				},
+				Annotations: map[string]string{"test": "test"},
+			}
+
+			manifest := &attestation.Manifest{
+				OriginalDescriptor: &v1.Descriptor{
+					MediaType: mediaType,
+				},
+				OriginalLayers: []*attestation.Layer{
+					originalLayer,
+				},
+				SubjectDescriptor: &v1.Descriptor{},
+			}
+			err := manifest.Add(ctx, signer, originalLayer.Statement, opts)
+			require.NoError(t, err)
+
+			newImg, err := manifest.BuildImage(attestation.WithReplacedLayers(tc.replace))
+			require.NoError(t, err)
+			mf, _ := newImg.RawManifest()
+			type Annotations struct {
+				Annotations map[string]string `json:"annotations"`
+			}
+			type Layers struct {
+				Layers []Annotations `json:"layers"`
+			}
+			l := &Layers{}
+			err = json.Unmarshal(mf, l)
+			require.NoError(t, err)
+			_, ok := l.Layers[0].Annotations["test"]
+			assert.Truef(t, ok, "missing annotations")
+		})
+	}
+}
+
+func TestSimpleStatementSigning(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	empty := types.MediaType("application/vnd.oci.empty.v1+json")
+	testCases := []struct {
+		name    string
+		replace bool
+	}{
+		{"replaced", true},
+		{"not replaced", false},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			opts := &attestation.SigningOptions{}
+			statement := &intoto.Statement{
+				StatementHeader: intoto.StatementHeader{
+					PredicateType: attestation.VSAPredicateType,
+				},
+			}
+			statement2 := &intoto.Statement{
+				StatementHeader: intoto.StatementHeader{
+					PredicateType: attestation.VSAPredicateType,
+				},
+			}
+			digest, err := v1.NewHash(test.UnsignedLinuxAMD64ImageDigest)
+			require.NoError(t, err)
+			subject := &v1.Descriptor{
+				MediaType: "application/vnd.oci.image.manifest.v1+json",
+				Digest:    digest,
+			}
+			manifest, err := attestation.NewManifest(subject)
+			require.NoError(t, err)
+			err = manifest.Add(ctx, signer, statement, opts)
+			require.NoError(t, err)
+
+			err = manifest.Add(ctx, signer, statement2, opts)
+			require.NoError(t, err)
+
+			// fake that the manfifest was loaded from a real image
+			manifest.OriginalLayers = manifest.SignedLayers
+			envelopes, err := attestation.ExtractEnvelopes(manifest, attestation.VSAPredicateType)
+			require.NoError(t, err)
+			assert.Len(t, envelopes, 2)
+
+			newImg, err := manifest.BuildImage(attestation.WithReplacedLayers(tc.replace))
+			require.NoError(t, err)
+			layers, err := newImg.Layers()
+			require.NoError(t, err)
+			if tc.replace {
+				assert.Len(t, layers, 2)
+			} else {
+				assert.Len(t, layers, 4)
+			}
+
+			newImgs, err := manifest.BuildReferringArtifacts()
+			require.NoError(t, err)
+			assert.Len(t, newImgs, 2)
+			for _, img := range newImgs {
+				mf, err := img.Manifest()
+				require.NoError(t, err)
+				assert.Contains(t, mf.ArtifactType, "application/vnd.in-toto")
+				assert.Contains(t, mf.ArtifactType, "+dsse")
+				assert.Equal(t, subject.MediaType, mf.MediaType)
+				assert.Equal(t, empty, mf.Config.MediaType)
+				assert.Equal(t, int64(2), mf.Config.Size)
+				assert.Equal(t, "{}", string(mf.Config.Data))
+				layers, err := img.Layers()
+				require.NoError(t, err)
+				assert.Len(t, layers, 1)
+			}
+			regServer := test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true))
+			defer regServer.Close()
+
+			u, err := url.Parse(regServer.URL)
+			require.NoError(t, err)
+
+			indexName := fmt.Sprintf("%s/repo:root", u.Host)
+			output, err := oci.ParseImageSpecs(indexName)
+			require.NoError(t, err)
+			artifacts, err := manifest.BuildReferringArtifacts()
+			require.NoError(t, err)
+			err = oci.SaveImagesNoTag(ctx, artifacts, output)
+			require.NoError(t, err)
+		})
+	}
+}

attestation/types.go

@@ -0,0 +1,163 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"crypto"
+	"encoding/base64"
+	"fmt"
+	"time"
+
+	"github.com/docker/attest/tlog"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	v02 "github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/v0.2"
+	slsav1 "github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/v1"
+	ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
+)
+
+const (
+	DockerReferenceType           = "vnd.docker.reference.type"
+	AttestationManifestType       = "attestation-manifest"
+	InTotoPredicateType           = "in-toto.io/predicate-type"
+	DockerReferenceDigest         = "vnd.docker.reference.digest"
+	DockerDSSEExtKind             = "application/vnd.docker.attestation-verification.v1+json"
+	OCIDescriptorDSSEMediaType    = ociv1.MediaTypeDescriptor + "+dsse"
+	InTotoReferenceLifecycleStage = "vnd.docker.lifecycle-stage"
+	LifecycleStageExperimental    = "experimental"
+)
+
+var base64Encoding = base64.StdEncoding.Strict()
+
+type Layer struct {
+	Statement   *intoto.Statement
+	Layer       v1.Layer
+	Annotations map[string]string
+}
+
+type Manifest struct {
+	OriginalDescriptor *v1.Descriptor
+	OriginalLayers     []*Layer
+
+	// accumulated during signing
+	SignedLayers []*Layer
+	// details of subject image
+	SubjectName       string
+	SubjectDescriptor *v1.Descriptor
+}
+
+type ManifestImageOptions struct {
+	// how to output the image
+	skipSubject   bool
+	replaceLayers bool
+	laxReferrers  bool
+}
+
+// the following types are needed until https://github.com/secure-systems-lab/dsse/pull/61 is merged.
+type Envelope struct {
+	PayloadType string       `json:"payloadType"`
+	Payload     string       `json:"payload"`
+	Signatures  []*Signature `json:"signatures"`
+}
+type Signature struct {
+	KeyID     string     `json:"keyid"`
+	Sig       string     `json:"sig"`
+	Extension *Extension `json:"extension,omitempty"`
+}
+type Extension struct {
+	Kind string               `json:"kind"`
+	Ext  *DockerDSSEExtension `json:"ext"`
+}
+
+type EnvelopeReference struct {
+	*Envelope
+	ResourceDescriptor *ResourceDescriptor `json:"resourceDescriptor"`
+}
+
+type ResourceDescriptor struct {
+	MediaType string            `json:"mediaType"`
+	Digest    map[string]string `json:"digest"`
+	URI       string            `json:"uri,omitempty"`
+}
+
+type AnnotatedStatement struct {
+	OCIDescriptor   *v1.Descriptor
+	InTotoStatement *intoto.Statement
+	Annotations     map[string]string
+}
+
+type DockerDSSEExtension struct {
+	TL *tlog.DockerTLExtension `json:"tl"`
+}
+
+type TransparencyLogKind string
+
+const (
+	RekorTransparencyLogKind = "rekor"
+)
+
+type VerifyOptions struct {
+	Keys            []*KeyMetadata      `json:"keys"`
+	SkipTL          bool                `json:"skip_tl"`
+	TransparencyLog TransparencyLogKind `json:"tl"`
+}
+
+type KeyMetadata struct {
+	ID            string     `json:"id"`
+	PEM           string     `json:"key"`
+	From          time.Time  `json:"from"`
+	To            *time.Time `json:"to"`
+	Status        string     `json:"status"`
+	SigningFormat string     `json:"signing-format"`
+	Distrust      bool       `json:"distrust,omitempty"`
+	publicKey     crypto.PublicKey
+}
+
+type (
+	Keys    []*KeyMetadata
+	KeysMap map[string]*KeyMetadata
+)
+
+type SigningOptions struct {
+	// set this in order to log to a transparency log
+	TransparencyLog tlog.TransparencyLog
+}
+
+type Options struct {
+	NoReferrers   bool
+	Attach        bool
+	ReferrersRepo string
+}
+
+func DSSEMediaType(predicateType string) (string, error) {
+	var predicateName string
+	switch predicateType {
+	case slsav1.PredicateSLSAProvenance:
+		predicateName = "provenance"
+	case v02.PredicateSLSAProvenance:
+		predicateName = "provenance"
+	case intoto.PredicateSPDX:
+		predicateName = "spdx"
+	case VSAPredicateType:
+		predicateName = "verification_summary"
+
+	default:
+		return "", fmt.Errorf("unknown predicate type %q", predicateType)
+	}
+
+	return fmt.Sprintf("application/vnd.in-toto.%s+dsse", predicateName), nil
+}

attestation/types_test.go

@@ -0,0 +1,60 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"fmt"
+	"testing"
+
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	v02 "github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/v0.2"
+	slsav1 "github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/v1"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestDSSEMediaType(t *testing.T) {
+	testcases := []struct {
+		name     string
+		expected string
+	}{
+		{
+			name:     slsav1.PredicateSLSAProvenance,
+			expected: "provenance",
+		},
+		{
+			name:     v02.PredicateSLSAProvenance,
+			expected: "provenance",
+		},
+		{
+			name:     intoto.PredicateSPDX,
+			expected: "spdx",
+		},
+		{
+			name:     VSAPredicateType,
+			expected: "verification_summary",
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			mt, err := DSSEMediaType(tc.name)
+			require.NoError(t, err)
+			assert.Equal(t, fmt.Sprintf("application/vnd.in-toto.%s+dsse", tc.expected), mt)
+		})
+	}
+}

attestation/verifier.go

@@ -0,0 +1,159 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"crypto"
+	"crypto/x509"
+	"fmt"
+
+	"github.com/docker/attest/signerverifier"
+	"github.com/docker/attest/tlog"
+	"github.com/docker/attest/tuf"
+	"github.com/secure-systems-lab/go-securesystemslib/dsse"
+)
+
+func WithTUFDownloader(tufDownloader tuf.Downloader) func(*verifier) {
+	return func(r *verifier) {
+		r.tufDownloader = tufDownloader
+	}
+}
+
+type SignatureVerifierFactory func(ctx context.Context, publicKey crypto.PublicKey, opts *VerifyOptions) (dsse.Verifier, error)
+
+func WithSignatureVerifierFactory(factory SignatureVerifierFactory) func(*verifier) {
+	return func(r *verifier) {
+		r.signatureVerifierFactory = factory
+	}
+}
+
+func WithLogVerifierFactory(factory LogVerifierFactory) func(*verifier) {
+	return func(r *verifier) {
+		r.logVerifierFactory = factory
+	}
+}
+
+type LogVerifierFactory func(ctx context.Context, opts *VerifyOptions) (tlog.TransparencyLog, error)
+
+func NewVerfier(options ...func(*verifier)) (Verifier, error) {
+	verifier := &verifier{}
+	for _, opt := range options {
+		opt(verifier)
+	}
+	return verifier, nil
+}
+
+type Verifier interface {
+	GetSignatureVerifier(ctx context.Context, publicKey crypto.PublicKey, opts *VerifyOptions) (dsse.Verifier, error)
+	GetLogVerifier(ctx context.Context, opts *VerifyOptions) (tlog.TransparencyLog, error)
+	VerifySignature(ctx context.Context, publicKey crypto.PublicKey, data []byte, signature []byte, opts *VerifyOptions) error
+	VerifyLog(ctx context.Context, keyMeta *KeyMetadata, data []byte, sig *Signature, opts *VerifyOptions) error
+}
+
+// ensure it has all the necessary methods.
+var _ Verifier = (*verifier)(nil)
+
+type verifier struct {
+	tufDownloader            tuf.Downloader
+	signatureVerifierFactory SignatureVerifierFactory
+	logVerifierFactory       LogVerifierFactory
+}
+
+// GetLogVerifier implements Verifier.
+func (v *verifier) GetLogVerifier(ctx context.Context, opts *VerifyOptions) (tlog.TransparencyLog, error) {
+	if v.logVerifierFactory != nil {
+		return v.logVerifierFactory(ctx, opts)
+	}
+	if opts.SkipTL {
+		return nil, nil
+	}
+	// TODO support other transparency logs
+	var transparencyLog tlog.TransparencyLog
+	switch opts.TransparencyLog {
+	case "", RekorTransparencyLogKind:
+		var err error
+		transparencyLog, err = tlog.NewRekorLog(tlog.WithTUFDownloader(v.tufDownloader))
+		if err != nil {
+			return nil, fmt.Errorf("error failed to create rekor verifier: %w", err)
+		}
+	default:
+		return nil, fmt.Errorf("unsupported transparency log: %s", opts.TransparencyLog)
+	}
+	return transparencyLog, nil
+}
+
+// GetSignatureVerifier implements Verifier.
+func (v *verifier) GetSignatureVerifier(ctx context.Context, publicKey crypto.PublicKey, opts *VerifyOptions) (dsse.Verifier, error) {
+	if v.signatureVerifierFactory != nil {
+		return v.signatureVerifierFactory(ctx, publicKey, opts)
+	}
+	// TODO: use details from opts to decide which algorithm to use here
+	ecdsaVerifier, err := signerverifier.NewECDSAVerifier(publicKey)
+	if err != nil {
+		return nil, fmt.Errorf("error failed to create ecdsa verifier: %w", err)
+	}
+	return ecdsaVerifier, nil
+}
+
+func (v *verifier) VerifySignature(ctx context.Context, publicKey crypto.PublicKey, data []byte, signature []byte, opts *VerifyOptions) error {
+	sigVerifier, err := v.GetSignatureVerifier(ctx, publicKey, opts)
+	if err != nil {
+		return fmt.Errorf("error failed to get verifier: %w", err)
+	}
+	return sigVerifier.Verify(ctx, data, signature)
+}
+
+func (v *verifier) VerifyLog(ctx context.Context, keyMeta *KeyMetadata, encPayload []byte, sig *Signature, opts *VerifyOptions) error {
+	if opts.SkipTL {
+		return nil
+	}
+	if sig.Extension == nil || sig.Extension.Kind == "" {
+		return fmt.Errorf("error missing signature extension")
+	}
+	if sig.Extension.Kind != DockerDSSEExtKind {
+		return fmt.Errorf("error unsupported signature extension kind: %s", sig.Extension.Kind)
+	}
+	transparencyLog, err := v.GetLogVerifier(ctx, opts)
+	if err != nil {
+		return fmt.Errorf("error failed to get transparency log verifier: %w", err)
+	}
+	if transparencyLog == nil {
+		return fmt.Errorf("error missing transparency log verifier")
+	}
+
+	// verify TL entry payload
+	publicKey, err := keyMeta.ParsedKey()
+	if err != nil {
+		return fmt.Errorf("error failed to parse public key: %w", err)
+	}
+	encodedPub, err := x509.MarshalPKIXPublicKey(publicKey)
+	if err != nil {
+		return fmt.Errorf("error failed to marshal public key: %w", err)
+	}
+	integratedTime, err := transparencyLog.VerifyEntry(ctx, sig.Extension.Ext.TL, encPayload, encodedPub)
+	if err != nil {
+		return fmt.Errorf("TL entry failed verification: %w", err)
+	}
+	if integratedTime.Before(keyMeta.From) {
+		return fmt.Errorf("key %s was not yet valid at TL log time %s (key valid from %s)", keyMeta.ID, integratedTime, keyMeta.From)
+	}
+	if keyMeta.To != nil && !integratedTime.Before(*keyMeta.To) {
+		return fmt.Errorf("key %s was already %s at TL log time %s (key %s at %s)", keyMeta.ID, keyMeta.Status, integratedTime, keyMeta.Status, *keyMeta.To)
+	}
+	return nil
+}

attestation/verifier_test.go

@@ -0,0 +1,71 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"reflect"
+	"testing"
+
+	"github.com/docker/attest/tlog"
+	"github.com/docker/attest/tuf"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_verifier_GetLogVerifier(t *testing.T) {
+	type fields struct {
+		tufDownloader            tuf.Downloader
+		signatureVerifierFactory SignatureVerifierFactory
+		logVerifierFactory       LogVerifierFactory
+	}
+	type args struct {
+		ctx  context.Context
+		opts *VerifyOptions
+	}
+	rekor, err := tlog.NewRekorLog()
+	require.NoError(t, err)
+	tests := []struct {
+		name    string
+		fields  fields
+		args    args
+		want    tlog.TransparencyLog
+		wantErr bool
+	}{
+		{name: "skip_tl true", fields: fields{}, args: args{ctx: context.Background(), opts: &VerifyOptions{SkipTL: true}}},
+		{name: "skip_tl false", fields: fields{}, args: args{ctx: context.Background(), opts: &VerifyOptions{SkipTL: false}}, want: rekor},
+		{name: "tl: rekor", fields: fields{logVerifierFactory: func(_ context.Context, _ *VerifyOptions) (tlog.TransparencyLog, error) {
+			return &tlog.Rekor{}, nil
+		}}, args: args{ctx: context.Background(), opts: &VerifyOptions{}}, want: &tlog.Rekor{}},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			v := &verifier{
+				tufDownloader:            tt.fields.tufDownloader,
+				signatureVerifierFactory: tt.fields.signatureVerifierFactory,
+				logVerifierFactory:       tt.fields.logVerifierFactory,
+			}
+			got, err := v.GetLogVerifier(tt.args.ctx, tt.args.opts)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("verifier.GetLogVerifier() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("verifier.GetLogVerifier() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}

attestation/verify.go

@@ -0,0 +1,99 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"context"
+	"crypto"
+	"encoding/base64"
+	"fmt"
+
+	"github.com/docker/attest/signerverifier"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/secure-systems-lab/go-securesystemslib/dsse"
+)
+
+func VerifyDSSE(ctx context.Context, verifier Verifier, env *Envelope, opts *VerifyOptions) ([]byte, error) {
+	// enforce payload type
+	if !ValidPayloadType(env.PayloadType) {
+		return nil, fmt.Errorf("unsupported payload type %s", env.PayloadType)
+	}
+
+	if len(env.Signatures) == 0 {
+		return nil, fmt.Errorf("no signatures found")
+	}
+
+	keys := make(map[string]*KeyMetadata, len(opts.Keys))
+	for _, key := range opts.Keys {
+		keys[key.ID] = key
+	}
+
+	payload, err := base64Encoding.DecodeString(env.Payload)
+	if err != nil {
+		return nil, fmt.Errorf("error failed to decode payload: %w", err)
+	}
+
+	encPayload := dsse.PAE(env.PayloadType, payload)
+	// verify signatures and transparency log entry
+	for _, sig := range env.Signatures {
+		// resolve public key used to sign
+		keyMeta, ok := keys[sig.KeyID]
+		if !ok {
+			return nil, fmt.Errorf("error key not found: %s", sig.KeyID)
+		}
+
+		if keyMeta.Distrust {
+			return nil, fmt.Errorf("key %s is distrusted", keyMeta.ID)
+		}
+		publicKey, err := keyMeta.ParsedKey()
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse public key: %w", err)
+		}
+		// decode signature
+		signature, err := base64.StdEncoding.Strict().DecodeString(sig.Sig)
+		if err != nil {
+			return nil, fmt.Errorf("error failed to decode signature: %w", err)
+		}
+
+		err = verifier.VerifySignature(ctx, publicKey, encPayload, signature, opts)
+		if err != nil {
+			return nil, fmt.Errorf("error failed to verify signature: %w", err)
+		}
+		if err := verifier.VerifyLog(ctx, keyMeta, encPayload, sig, opts); err != nil {
+			return nil, fmt.Errorf("error failed to verify transparency log entry: %w", err)
+		}
+	}
+
+	return payload, nil
+}
+
+func ValidPayloadType(payloadType string) bool {
+	return payloadType == intoto.PayloadType || payloadType == ociv1.MediaTypeDescriptor
+}
+
+func (km *KeyMetadata) ParsedKey() (crypto.PublicKey, error) {
+	if km.publicKey != nil {
+		return km.publicKey, nil
+	}
+	publicKey, err := signerverifier.ParsePublicKey([]byte(km.PEM))
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse public key: %w", err)
+	}
+	km.publicKey = publicKey
+	return publicKey, nil
+}

attestation/verify_test.go

@@ -1,11 +1,27 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package attestation_test
 
 import (
 	"encoding/base64"
 	"testing"
 
+	"github.com/docker/attest/attestation"
 	"github.com/docker/attest/internal/test"
-	"github.com/docker/attest/pkg/attestation"
 	intoto "github.com/in-toto/in-toto-golang/in_toto"
 	ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/stretchr/testify/assert"
@@ -35,12 +51,14 @@ func TestVerifyUnsignedAttestation(t *testing.T) {
 	payload := []byte("payload")
 	env := &attestation.Envelope{
 		// no signatures
-		Signatures:  []attestation.Signature{},
+		Signatures:  []*attestation.Signature{},
 		Payload:     base64.StdEncoding.EncodeToString(payload),
 		PayloadType: intoto.PayloadType,
 	}
-
-	_, err := attestation.VerifyDSSE(ctx, env, attestation.KeysMap{})
+	opts := &attestation.VerifyOptions{
+		Keys: attestation.Keys{},
+	}
+	_, err := attestation.VerifyDSSE(ctx, nil, env, opts)
 	assert.Error(t, err)
 	assert.Contains(t, err.Error(), "no signatures")
 }

attestation/vsa.go

@@ -0,0 +1,79 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attestation
+
+import (
+	"fmt"
+
+	"github.com/docker/attest/version"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/package-url/packageurl-go"
+)
+
+const (
+	VSAPredicateType = "https://slsa.dev/verification_summary/v1"
+)
+
+type VSAPredicate struct {
+	Verifier           VSAVerifier          `json:"verifier"`
+	TimeVerified       string               `json:"timeVerified"`
+	ResourceURI        string               `json:"resourceUri"`
+	Policy             VSAPolicy            `json:"policy"`
+	InputAttestations  []ResourceDescriptor `json:"inputAttestations,omitempty"`
+	VerificationResult string               `json:"verificationResult"`
+	VerifiedLevels     []string             `json:"verifiedLevels"`
+}
+
+type VSAVerifier struct {
+	ID      string          `json:"id"`
+	Version VerifierVersion `json:"version"`
+}
+
+type VerifierVersion map[string]string
+
+type VSAPolicy struct {
+	URI              string            `json:"uri,omitempty"`
+	Digest           map[string]string `json:"digest"`
+	DownloadLocation string            `json:"downloadLocation,omitempty"`
+}
+
+func ToVSAResourceURI(sub intoto.Subject) (string, error) {
+	// parse purl
+	purl, err := packageurl.FromString(sub.Name)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse package url: %w", err)
+	}
+	quals := purl.Qualifiers.Map()
+	if quals["digest"] == "" {
+		quals["digest"] = "sha256:" + sub.Digest["sha256"]
+	}
+	purl.Qualifiers = packageurl.QualifiersFromMap(quals)
+	return purl.String(), nil
+}
+
+func GetVerifierVersion(fetcher version.Fetcher) (VerifierVersion, error) {
+	attestVersion, err := fetcher.Get()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get attest version: %w", err)
+	}
+	if attestVersion == nil {
+		return nil, nil
+	}
+	return VerifierVersion{
+		version.ThisModulePath: attestVersion.String(),
+	}, nil
+}

codecov.yml

@@ -0,0 +1,5 @@
+ignore:
+  - "internal/test"
+coverage:
+  status:
+    patch: false

example_sign_test.go

@@ -0,0 +1,99 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attest_test
+
+import (
+	"context"
+
+	"github.com/docker/attest"
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/signerverifier"
+	"github.com/docker/attest/tlog"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+)
+
+func ExampleSignStatements_remote() {
+	// configure signerverifier
+	// local signer (unsafe for production)
+	signer, err := signerverifier.GenKeyPair()
+	if err != nil {
+		panic(err)
+	}
+	// example using AWS KMS signer
+	// aws_arn := "arn:aws:kms:us-west-2:123456789012:key/12345678-1234-1234-1234-123456789012"
+	// aws_region := "us-west-2"
+	// signer, err := signerverifier.GetAWSSigner(cmd.Context(), aws_arn, aws_region)
+
+	// configure signing options
+
+	// use rekor transparency log wit static rekor public key (see options to use dynamic rekor public key)
+	rekor, err := tlog.NewRekorLog()
+	if err != nil {
+		panic(err)
+	}
+	opts := &attestation.SigningOptions{
+		TransparencyLog: rekor, // unset this to disable signature transparency logging
+	}
+
+	// load image index with unsigned attestation-manifests
+	ref := "docker/image-signer-verifier:latest"
+	attIdx, err := oci.IndexFromRemote(context.Background(), ref)
+	if err != nil {
+		panic(err)
+	}
+	// example for local image index
+	// path := "/myimage"
+	// attIdx, err = oci.IndexFromPath(path)
+	// if err != nil {
+	// 	panic(err)
+	// }
+
+	// sign all attestations in an image index
+	signedManifests, err := attest.SignStatements(context.Background(), attIdx.Index, signer, opts)
+	if err != nil {
+		panic(err)
+	}
+	signedIndex := attIdx.Index
+	signedIndex, err = attestation.UpdateIndexImages(signedIndex, signedManifests)
+	if err != nil {
+		panic(err)
+	}
+
+	// push image index with signed attestation-manifests
+	err = oci.PushIndexToRegistry(context.Background(), signedIndex, ref)
+	if err != nil {
+		panic(err)
+	}
+	// output image index to filesystem (optional)
+	path := "/myimage"
+	idx := v1.ImageIndex(empty.Index)
+	idx = mutate.AppendManifests(idx, mutate.IndexAddendum{
+		Add: signedIndex,
+		Descriptor: v1.Descriptor{
+			Annotations: map[string]string{
+				oci.OCIReferenceTarget: attIdx.Name,
+			},
+		},
+	})
+	err = oci.SaveIndexAsOCILayout(idx, path)
+	if err != nil {
+		panic(err)
+	}
+}

example_verify_test.go

@@ -0,0 +1,70 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package attest_test
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/docker/attest"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/policy"
+	"github.com/docker/attest/tuf"
+)
+
+func ExampleVerify_remote() {
+	// create a tuf client
+	home, err := os.UserHomeDir()
+	if err != nil {
+		panic(err)
+	}
+	tufOutputPath := filepath.Join(home, ".docker", "tuf")
+	tufClientOpts := tuf.NewDockerDefaultClientOptions(tufOutputPath)
+
+	// create a resolver for remote attestations
+	image := "registry-1.docker.io/library/notary:server"
+	platform := "linux/amd64"
+
+	// configure policy options
+	opts := &policy.Options{
+		TUFClientOptions: tufClientOpts,
+		LocalTargetsDir:  filepath.Join(home, ".docker", "policy"), // location to store policy files downloaded from TUF
+		LocalPolicyDir:   "",                                       // overrides TUF policy for local policy files if set
+		PolicyID:         "",                                       // set to ignore policy mapping and select a policy by id
+		DisableTUF:       false,                                    // set to disable TUF and rely on local policy files
+	}
+
+	src, err := oci.ParseImageSpec(image, oci.WithPlatform(platform))
+	if err != nil {
+		panic(err)
+	}
+	// verify attestations
+	result, err := attest.Verify(context.Background(), src, opts)
+	if err != nil {
+		panic(err)
+	}
+	switch result.Outcome {
+	case attest.OutcomeSuccess:
+		fmt.Println("policy passed")
+	case attest.OutcomeNoPolicy:
+		fmt.Println("no policy for image")
+	case attest.OutcomeFailure:
+		fmt.Println("policy failed")
+	}
+}

go.mod

@@ -1,80 +1,95 @@
 module github.com/docker/attest
 
-go 1.22.1
+go 1.22.8
 
 require (
-	github.com/aws/aws-sdk-go-v2/config v1.27.11
-	github.com/containerd/containerd v1.7.14
-	github.com/distribution/reference v0.5.0
+	github.com/Masterminds/semver/v3 v3.3.0
+	github.com/aws/aws-sdk-go-v2/config v1.28.5
+	github.com/awslabs/amazon-ecr-credential-helper/ecr-login v0.0.0-20231024185945-8841054dbdb8
+	github.com/containerd/containerd/v2 v2.0.0
+	github.com/containerd/platforms v1.0.0-rc.0
+	github.com/distribution/reference v0.6.0
+	github.com/docker-library/bashbrew v0.1.12
+	github.com/go-git/go-git/v5 v5.12.0
 	github.com/go-openapi/runtime v0.28.0
 	github.com/go-openapi/strfmt v0.23.0
-	github.com/google/go-containerregistry v0.19.1
-	github.com/hashicorp/go-cleanhttp v0.5.2
+	github.com/google/go-containerregistry v0.20.2
 	github.com/in-toto/in-toto-golang v0.9.0
-	github.com/open-policy-agent/opa v0.63.0
+	github.com/open-policy-agent/opa v0.70.0
 	github.com/opencontainers/image-spec v1.1.0
-	github.com/package-url/packageurl-go v0.1.2
-	github.com/pkg/errors v0.9.1
+	github.com/package-url/packageurl-go v0.1.3
 	github.com/secure-systems-lab/go-securesystemslib v0.8.0
-	github.com/sigstore/cosign/v2 v2.2.4
+	github.com/sigstore/cosign/v2 v2.4.1
 	github.com/sigstore/rekor v1.3.6
-	github.com/sigstore/sigstore/pkg/signature/kms/aws v1.8.3
+	github.com/sigstore/sigstore v1.8.10
+	github.com/sigstore/sigstore/pkg/signature/kms/aws v1.8.10
+	github.com/sigstore/sigstore/pkg/signature/kms/gcp v1.8.10
 	github.com/stretchr/testify v1.9.0
-	github.com/testcontainers/testcontainers-go v0.30.0
-	github.com/testcontainers/testcontainers-go/modules/registry v0.30.0
-	github.com/theupdateframework/go-tuf/v2 v2.0.0-20240402164131-b2e024ad4752
-	gopkg.in/yaml.v3 v3.0.1
+	github.com/theupdateframework/go-tuf/v2 v2.0.2
+	google.golang.org/api v0.205.0
 	sigs.k8s.io/yaml v1.4.0
 )
 
-replace github.com/theupdateframework/go-tuf/v2 => github.com/mrjoelkamp/go-tuf/v2 v2.0.1 // for https://github.com/theupdateframework/go-tuf/pull/632
+// fork with changes to support ArtifactType (https://github.com/google/go-containerregistry/pull/1931)
+replace github.com/google/go-containerregistry => github.com/docker/go-containerregistry v0.0.0-20240808132857-c8bfc44af7c8
 
 require (
-	dario.cat/mergo v1.0.0 // indirect
-	github.com/Azure/go-ansiterm v0.0.0-20230124172434-306776ec8161 // indirect
-	github.com/Microsoft/go-winio v0.6.1 // indirect
-	github.com/Microsoft/hcsshim v0.11.4 // indirect
+	cloud.google.com/go v0.116.0 // indirect
+	cloud.google.com/go/auth v0.10.1 // indirect
+	cloud.google.com/go/auth/oauth2adapt v0.2.5 // indirect
+	cloud.google.com/go/compute/metadata v0.5.2 // indirect
+	cloud.google.com/go/iam v1.2.1 // indirect
+	cloud.google.com/go/kms v1.20.0 // indirect
+	cloud.google.com/go/longrunning v0.6.1 // indirect
+	dario.cat/mergo v1.0.1 // indirect
+	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/Microsoft/hcsshim v0.12.9 // indirect
 	github.com/OneOfOne/xxhash v1.2.8 // indirect
-	github.com/agnivade/levenshtein v1.1.1 // indirect
+	github.com/ProtonMail/go-crypto v1.0.0 // indirect
+	github.com/agnivade/levenshtein v1.2.0 // indirect
 	github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2 // indirect
-	github.com/aws/aws-sdk-go-v2 v1.26.1 // indirect
-	github.com/aws/aws-sdk-go-v2/credentials v1.17.11 // indirect
-	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.16.1 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/configsources v1.3.5 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.6.5 // indirect
-	github.com/aws/aws-sdk-go-v2/internal/ini v1.8.0 // indirect
-	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.11.2 // indirect
-	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.11.7 // indirect
-	github.com/aws/aws-sdk-go-v2/service/kms v1.30.0 // indirect
-	github.com/aws/aws-sdk-go-v2/service/sso v1.20.5 // indirect
-	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.23.4 // indirect
-	github.com/aws/aws-sdk-go-v2/service/sts v1.28.6 // indirect
-	github.com/aws/smithy-go v1.20.2 // indirect
+	github.com/aws/aws-sdk-go-v2 v1.32.5 // indirect
+	github.com/aws/aws-sdk-go-v2/credentials v1.17.46 // indirect
+	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.16.20 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.3.24 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.6.24 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/ini v1.8.1 // indirect
+	github.com/aws/aws-sdk-go-v2/service/ecr v1.29.1 // indirect
+	github.com/aws/aws-sdk-go-v2/service/ecrpublic v1.24.1 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/accept-encoding v1.12.1 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.12.5 // indirect
+	github.com/aws/aws-sdk-go-v2/service/kms v1.37.2 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sso v1.24.6 // indirect
+	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.28.5 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sts v1.33.1 // indirect
+	github.com/aws/smithy-go v1.22.1 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/blang/semver v3.5.1+incompatible // indirect
-	github.com/cenkalti/backoff/v4 v4.2.1 // indirect
-	github.com/cespare/xxhash/v2 v2.2.0 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/cloudflare/circl v1.3.8 // indirect
+	github.com/containerd/containerd v1.7.23 // indirect
+	github.com/containerd/errdefs v1.0.0 // indirect
 	github.com/containerd/log v0.1.0 // indirect
-	github.com/containerd/stargz-snapshotter/estargz v0.14.3 // indirect
-	github.com/cpuguy83/dockercfg v0.3.1 // indirect
-	github.com/cyberphone/json-canonicalization v0.0.0-20231011164504-785e29786b46 // indirect
+	github.com/containerd/stargz-snapshotter/estargz v0.15.1 // indirect
+	github.com/cyberphone/json-canonicalization v0.0.0-20231217050601-ba74d44ecf5f // indirect
+	github.com/cyphar/filepath-securejoin v0.2.4 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
 	github.com/digitorus/pkcs7 v0.0.0-20230818184609-3a137a874352 // indirect
 	github.com/digitorus/timestamp v0.0.0-20231217203849-220c5c2851b7 // indirect
-	github.com/docker/cli v24.0.7+incompatible // indirect
+	github.com/docker/cli v27.1.1+incompatible // indirect
 	github.com/docker/distribution v2.8.3+incompatible // indirect
-	github.com/docker/docker v25.0.5+incompatible // indirect
-	github.com/docker/docker-credential-helpers v0.8.0 // indirect
-	github.com/docker/go-connections v0.5.0 // indirect
-	github.com/docker/go-units v0.5.0 // indirect
+	github.com/docker/docker-credential-helpers v0.8.1 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/emirpasic/gods v1.18.1 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/fsnotify/fsnotify v1.7.0 // indirect
 	github.com/go-chi/chi v4.1.2+incompatible // indirect
+	github.com/go-git/gcfg v1.5.1-0.20230307220236-3a3c6141e376 // indirect
+	github.com/go-git/go-billy/v5 v5.5.0 // indirect
 	github.com/go-ini/ini v1.67.0 // indirect
-	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/go-jose/go-jose/v4 v4.0.4 // indirect
+	github.com/go-logr/logr v1.4.2 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
-	github.com/go-ole/go-ole v1.2.6 // indirect
 	github.com/go-openapi/analysis v0.23.0 // indirect
 	github.com/go-openapi/errors v0.22.0 // indirect
 	github.com/go-openapi/jsonpointer v0.21.0 // indirect
@@ -84,91 +99,101 @@ require (
 	github.com/go-openapi/swag v0.23.0 // indirect
 	github.com/go-openapi/validate v0.24.0 // indirect
 	github.com/gobwas/glob v0.2.3 // indirect
-	github.com/gogo/protobuf v1.3.2 // indirect
-	github.com/golang/protobuf v1.5.4 // indirect
+	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
 	github.com/golang/snappy v0.0.4 // indirect
-	github.com/google/certificate-transparency-go v1.1.8 // indirect
+	github.com/google/certificate-transparency-go v1.2.1 // indirect
+	github.com/google/s2a-go v0.1.8 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.4 // indirect
+	github.com/googleapis/gax-go/v2 v2.13.0 // indirect
 	github.com/gorilla/mux v1.8.1 // indirect
-	github.com/hashicorp/go-retryablehttp v0.7.5 // indirect
+	github.com/hashicorp/go-cleanhttp v0.5.2 // indirect
+	github.com/hashicorp/go-retryablehttp v0.7.7 // indirect
 	github.com/hashicorp/hcl v1.0.1-vault-5 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/jbenet/go-context v0.0.0-20150711004518-d14ea06fba99 // indirect
 	github.com/jedisct1/go-minisign v0.0.0-20230811132847-661be99b8267 // indirect
-	github.com/jellydator/ttlcache/v3 v3.2.0 // indirect
+	github.com/jellydator/ttlcache/v3 v3.3.0 // indirect
+	github.com/jmespath/go-jmespath v0.4.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
-	github.com/klauspost/compress v1.17.4 // indirect
-	github.com/letsencrypt/boulder v0.0.0-20231026200631-000cd05d5491 // indirect
-	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect
+	github.com/kevinburke/ssh_config v1.2.0 // indirect
+	github.com/klauspost/compress v1.17.11 // indirect
+	github.com/letsencrypt/boulder v0.0.0-20240620165639-de9c06129bec // indirect
 	github.com/magiconair/properties v1.8.7 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mitchellh/go-homedir v1.1.0 // indirect
 	github.com/mitchellh/mapstructure v1.5.0 // indirect
-	github.com/moby/patternmatcher v0.6.0 // indirect
-	github.com/moby/sys/sequential v0.5.0 // indirect
-	github.com/moby/sys/user v0.1.0 // indirect
-	github.com/moby/term v0.5.0 // indirect
-	github.com/morikuni/aec v1.0.0 // indirect
+	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
 	github.com/nozzle/throttler v0.0.0-20180817012639-2ea982251481 // indirect
 	github.com/oklog/ulid v1.3.1 // indirect
 	github.com/opencontainers/go-digest v1.0.0 // indirect
 	github.com/opentracing/opentracing-go v1.2.0 // indirect
-	github.com/pelletier/go-toml/v2 v2.1.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.3 // indirect
+	github.com/pjbgf/sha1cd v0.3.0 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
-	github.com/power-devops/perfstat v0.0.0-20210106213030-5aafc221ea8c // indirect
-	github.com/prometheus/client_golang v1.19.0 // indirect
-	github.com/prometheus/client_model v0.6.0 // indirect
-	github.com/prometheus/common v0.51.1 // indirect
-	github.com/prometheus/procfs v0.12.0 // indirect
+	github.com/prometheus/client_golang v1.20.5 // indirect
+	github.com/prometheus/client_model v0.6.1 // indirect
+	github.com/prometheus/common v0.55.0 // indirect
+	github.com/prometheus/procfs v0.15.1 // indirect
 	github.com/rcrowley/go-metrics v0.0.0-20201227073835-cf1acfcdf475 // indirect
+	github.com/rogpeppe/go-internal v1.13.1 // indirect
 	github.com/sagikazarmark/locafero v0.4.0 // indirect
 	github.com/sagikazarmark/slog-shim v0.1.0 // indirect
 	github.com/sassoftware/relic v7.2.1+incompatible // indirect
+	github.com/sergi/go-diff v1.3.2-0.20230802210424-5b0b94c5c0d3 // indirect
 	github.com/shibumi/go-pathspec v1.3.0 // indirect
-	github.com/shirou/gopsutil/v3 v3.23.12 // indirect
-	github.com/shoenig/go-m1cpu v0.1.6 // indirect
-	github.com/sigstore/sigstore v1.8.3 // indirect
+	github.com/sigstore/protobuf-specs v0.3.2 // indirect
 	github.com/sigstore/timestamp-authority v1.2.2 // indirect
 	github.com/sirupsen/logrus v1.9.3 // indirect
+	github.com/skeema/knownhosts v1.2.2 // indirect
 	github.com/sourcegraph/conc v0.3.0 // indirect
 	github.com/spf13/afero v1.11.0 // indirect
 	github.com/spf13/cast v1.6.0 // indirect
-	github.com/spf13/cobra v1.8.0 // indirect
+	github.com/spf13/cobra v1.8.1 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	github.com/spf13/viper v1.18.2 // indirect
+	github.com/spf13/viper v1.19.0 // indirect
 	github.com/subosito/gotenv v1.6.0 // indirect
 	github.com/syndtr/goleveldb v1.0.1-0.20220721030215-126854af5e6d // indirect
 	github.com/tchap/go-patricia/v2 v2.3.1 // indirect
 	github.com/theupdateframework/go-tuf v0.7.0 // indirect
 	github.com/titanous/rocacheck v0.0.0-20171023193734-afe73141d399 // indirect
-	github.com/tklauser/go-sysconf v0.3.12 // indirect
-	github.com/tklauser/numcpus v0.6.1 // indirect
 	github.com/transparency-dev/merkle v0.0.2 // indirect
 	github.com/vbatts/tar-split v0.11.5 // indirect
+	github.com/xanzy/ssh-agent v0.3.3 // indirect
 	github.com/xeipuuv/gojsonpointer v0.0.0-20190905194746-02993c407bfb // indirect
 	github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415 // indirect
 	github.com/yashtewari/glob-intersection v0.2.0 // indirect
-	github.com/yusufpapurcu/wmi v1.2.3 // indirect
-	go.mongodb.org/mongo-driver v1.14.0 // indirect
-	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.49.0 // indirect
-	go.opentelemetry.io/otel v1.24.0 // indirect
-	go.opentelemetry.io/otel/metric v1.24.0 // indirect
-	go.opentelemetry.io/otel/sdk v1.24.0 // indirect
-	go.opentelemetry.io/otel/trace v1.24.0 // indirect
+	go.mongodb.org/mongo-driver v1.15.0 // indirect
+	go.opencensus.io v0.24.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc v0.56.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.56.0 // indirect
+	go.opentelemetry.io/otel v1.31.0 // indirect
+	go.opentelemetry.io/otel/metric v1.31.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.31.0 // indirect
+	go.opentelemetry.io/otel/trace v1.31.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.27.0 // indirect
-	golang.org/x/crypto v0.22.0 // indirect
-	golang.org/x/exp v0.0.0-20231108232855-2478ac86f678 // indirect
-	golang.org/x/mod v0.16.0 // indirect
-	golang.org/x/sync v0.7.0 // indirect
-	golang.org/x/sys v0.19.0 // indirect
-	golang.org/x/term v0.19.0 // indirect
-	golang.org/x/text v0.14.0 // indirect
-	golang.org/x/tools v0.19.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20240318140521-94a12d6c2237 // indirect
-	google.golang.org/grpc v1.62.1 // indirect
-	google.golang.org/protobuf v1.33.0 // indirect
-	gopkg.in/go-jose/go-jose.v2 v2.6.3 // indirect
+	golang.org/x/crypto v0.28.0 // indirect
+	golang.org/x/exp v0.0.0-20240613232115-7f521ea00fb8 // indirect
+	golang.org/x/mod v0.21.0 // indirect
+	golang.org/x/net v0.30.0 // indirect
+	golang.org/x/oauth2 v0.23.0 // indirect
+	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sys v0.26.0 // indirect
+	golang.org/x/term v0.25.0 // indirect
+	golang.org/x/text v0.19.0 // indirect
+	golang.org/x/time v0.7.0 // indirect
+	google.golang.org/genproto v0.0.0-20241021214115-324edc3d5d38 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20241015192408-796eee8c2d53 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20241021214115-324edc3d5d38 // indirect
+	google.golang.org/grpc v1.67.1 // indirect
+	google.golang.org/protobuf v1.35.1 // indirect
 	gopkg.in/ini.v1 v1.67.0 // indirect
-	gopkg.in/yaml.v2 v2.4.0 // indirect
-	k8s.io/klog/v2 v2.120.1 // indirect
+	gopkg.in/warnings.v0 v0.1.2 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+	gotest.tools/v3 v3.5.1 // indirect
+	k8s.io/klog/v2 v2.130.1 // indirect
+	pault.ag/go/debian v0.12.0 // indirect
+	pault.ag/go/topsort v0.1.1 // indirect
 )

internal/embed/embedded-roots/1.root-dev.json

@@ -1,42 +1,42 @@
 {
  "signatures": [
   {
-   "keyid": "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09",
-   "sig": "3064023037bbb03c3472b140572a7d5a2895bd80e74435bbcb7053949731f81b104c6d05a0876590cd6a2e94d7ed619426a2f6fa02303adc8c9006fa5506fdd7ea87d2960074a537ad8bf2459f2863e806b47682cbb2f9b01b7502eaf5437a1a68fdaaeac114"
+   "keyid": "76d0a7e1ff8617ce99627d0fa5c9809f2c0f0d52e0bf65c7b84c031608d25221",
+   "sig": "3065023000f7d0a866576e94eaabc173b9233d4c8fcfa495527088f9022dff5a553f7a457da1015a6d0fc714f84848ec627387360231009fa70b2eebbe15241a2ec9b96a094ebd28661e30b8c3d1eab8d694df2b340bda511c489393630c9a9dacde42c99e9fa1"
   }
  ],
  "signed": {
   "_type": "root",
   "consistent_snapshot": true,
-  "expires": "2034-04-02T17:00:22Z",
+  "expires": "2034-05-29T20:14:11Z",
   "keys": {
-   "198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3": {
-    "keytype": "ecdsa",
-    "keyval": {
-     "public": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEgDpP6O0sEt2R+l84WlfmqPBsFSby\nxJsJ6YmeUVgDk/wk9++8IAR6YBYewaKye56gMnIYjTFbyOI8WomA2NQFBw==\n-----END PUBLIC KEY-----\n"
-    },
-    "scheme": "ecdsa-sha2-nistp256",
-    "x-tuf-on-ci-online-uri": "awskms:arn:aws:kms:us-east-1:175142243308:key/fbd8dab6-5677-4b57-87e6-8369c45b3b61"
-   },
-   "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09": {
+   "76d0a7e1ff8617ce99627d0fa5c9809f2c0f0d52e0bf65c7b84c031608d25221": {
     "keytype": "ecdsa",
     "keyval": {
      "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE3+asmp2GD6UijwWvMezwVG/BwFLuQa3o\nT6eRxFvkILGpVDbZ92ZYWidHl9LZ/eJUjhIjuVEkNVKoenw5KjKl8veP3MthZrQA\nSkYytOIwkidZo9Rk2dczbDcFSJvLGsmd\n-----END PUBLIC KEY-----\n"
     },
     "scheme": "ecdsa-sha2-nistp384",
     "x-tuf-on-ci-keyowner": "@mrjoelkamp"
+   },
+   "bdd1703ecbde8812614b112a6551d58de3ad681048fd90fca2a3e491edd8afe5": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEgDpP6O0sEt2R+l84WlfmqPBsFSby\nxJsJ6YmeUVgDk/wk9++8IAR6YBYewaKye56gMnIYjTFbyOI8WomA2NQFBw==\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp256",
+    "x-tuf-on-ci-online-uri": "awskms:arn:aws:kms:us-east-1:175142243308:key/fbd8dab6-5677-4b57-87e6-8369c45b3b61"
    }
   },
   "roles": {
    "root": {
     "keyids": [
-     "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09"
+     "76d0a7e1ff8617ce99627d0fa5c9809f2c0f0d52e0bf65c7b84c031608d25221"
     ],
     "threshold": 1
    },
    "snapshot": {
     "keyids": [
-     "198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3"
+     "bdd1703ecbde8812614b112a6551d58de3ad681048fd90fca2a3e491edd8afe5"
     ],
     "threshold": 1,
     "x-tuf-on-ci-expiry-period": 3650,
@@ -44,13 +44,13 @@
    },
    "targets": {
     "keyids": [
-     "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09"
+     "76d0a7e1ff8617ce99627d0fa5c9809f2c0f0d52e0bf65c7b84c031608d25221"
     ],
     "threshold": 1
    },
    "timestamp": {
     "keyids": [
-     "198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3"
+     "bdd1703ecbde8812614b112a6551d58de3ad681048fd90fca2a3e491edd8afe5"
     ],
     "threshold": 1,
     "x-tuf-on-ci-expiry-period": 3650,

internal/embed/embedded-roots/1.root.json

@@ -0,0 +1,152 @@
+{
+ "signatures": [
+  {
+   "keyid": "08d6f4ca1d0be93a6ceddca15051c0aeec6b98c73e29f3a714de301042d6eeee",
+   "sig": "306502307ddba543fbd1b9e2ccbee604349024e62bbb1a37906bbd5605a7403fbdb51b701b52f5fcd1b0a0ebfaeef97fa9c344f8023100c37ab675fe96b3976469a5e0cc8a5ffb5d8d6de15020f493d7cf28b0c7e60f450b65c02bfbac0e40642863a1ae3bfa4a"
+  },
+  {
+   "keyid": "3ebd40525193d7628d0b9eccd4771df7297bc87519ec6f312863bb4470966bea",
+   "sig": "3065023100bc963925fb139dd65653b5e9640572876c5bcd0a3f8bb81e4b0cbd397c10ec4fa0aed7942d77ec78b865e14c72e20e76023043ce7ff39067f054d6d2eaca5dd5176b2c25e27bd763b4ef873aaf4c75762bfb085bb766613692b68206ea0df2863426"
+  },
+  {
+   "keyid": "9c8e1be7d8d0e30656adc81ac201e05cb47a5a097d4d301fd121b77c320231c4",
+   "sig": "306502307e82d7bc0c66074b06cfc13bac3761c8f677eef252c08448eb33c0249569500e8be2a1ae78c87b5888ed80d088f97fbb023100c358c6ebe18d237bae9a9daeaf2db82297cda8eca635fc22719142740fb23b32eac0341754dd2a85b684c46e3a087ada"
+  },
+  {
+   "keyid": "373d0a38247919a78cf400cf9a90abb9aa23a3c3dce1deee995fdd6a81507117",
+   "sig": "306402305d9b5fdf3b24240b266a7ae7e02bbcadce8e06f8c111dcef03282faa0baaffb8114653cecda3da115d7859f657508d4f02304b5939fc4404f9e1e8b9d3eb49e195a779b501bd4000cef6cff7a8e657020176dae99cce2a7300b88e549d427278309c"
+  },
+  {
+   "keyid": "48a873aa6c4189804228590af4d48ee5ad3b76417592efdbcef2532401925669",
+   "sig": "306402306bc5f44621c0d6e18ce16155ebc7890def8fb283859175f7a8425190f0f233e4270b2688df05b017cfc852dee30f9f5b023016572d059d6f27968976df2aaff8238ee0970cea229e5ef30350f2c91347b04e794683da69cf6afe6cf9206dcebc81f4"
+  }
+ ],
+ "signed": {
+  "_type": "root",
+  "consistent_snapshot": true,
+  "expires": "2025-06-04T15:05:22Z",
+  "keys": {
+   "08d6f4ca1d0be93a6ceddca15051c0aeec6b98c73e29f3a714de301042d6eeee": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEC4ggHc/D9koyS1/AMNsMGiydM2jDzdsI\nrkC/nyZf8d4UtYJJRxuFRfmyKw9Mh0Ulw/IIyf8ZW2NsnkHgJwGre9/Ici6uomOX\n8yAOlX0Du/oAa7v4igCG7tsW0Z1ljAID\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@jeanlaurent"
+   },
+   "2ff207ae7d7b595ef69589622067ef5b6668e1a43081377d942ed8749fa919b4": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE5pyJ/RXlRO/a2WBSAprikm+VVPqZGC1M\nqgVXE3avwqb9d9lPc9Cphfd4CIAzPCKgeUkGMzQWcC1OwVjOwiB+GRq2Owf7T8pa\nKUe/zRoLjAlUnzUITHP226L1DmQ6Swos\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@kipz"
+   },
+   "373d0a38247919a78cf400cf9a90abb9aa23a3c3dce1deee995fdd6a81507117": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAER2zST05lNvybLsSe4UA/hiUrJbA6aFyz\nDimwewwbHvw+gt29EHYtHPqTlO/hSZD5vqZ94Cga9rDsOm3eI5bPkPHApUjw4W7u\n5lDnxuuFKluQ7EiUbswUN0ONTPnmY7Wo\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@binman-docker"
+   },
+   "3ebd40525193d7628d0b9eccd4771df7297bc87519ec6f312863bb4470966bea": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAE9C53JKQtD1RYLiSwmR4XRhI7jf28W9TK\nhV3aXW0Z87JyJ4wGNOFnGRE6PuEh7Bbu4ecH0PpsEoirWzzRIgBMR3yHVCSkFBDu\nqfycsInCTAS1jvzLiDHciKXENxAWARHj\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@ingshtrom"
+   },
+   "48a873aa6c4189804228590af4d48ee5ad3b76417592efdbcef2532401925669": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEpQrE8o+fz6kBrs3TD6zqcDPwRZf3FxOX\n+SiT0k3SL1JHsMbxwFAKq+wJzqpqbhzFySuO1VVT93xNDd/rmjEU6HSY7wvT0m/l\nZ0S7yIwl3UnlplzKUYg/8wWJM0C2Qdpj\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@cdupuis"
+   },
+   "6132f1f2dd14bf3e9ba1a8df4c8435a77d2fd57f4a99bbb699ae61f85907818e": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEkFPn3WTH/xVIEFhdP/TCqtnuiOqdgb/v\nEIBjng1TBCVmr7NnW4y4bdZG4Tf9OVTSqlJzuUFThJT/JQR3M7xEzW9WJqUfBTS1\nUuF980elHtMpRkS3NtRp/T0IrkH7+COa\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@jonnystoten"
+   },
+   "9c8e1be7d8d0e30656adc81ac201e05cb47a5a097d4d301fd121b77c320231c4": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEWDreR+iXRtTStv5zmCLGoSmvvfV9/agY\nkx4O1XpRinBwAAA/IO4MI+YCoY0EQpKlSxl0DoVe6hmiXq2ezjTbebGDO66+fTZH\nkrr4KiCsZ8QcdPAR2cUvXkgyBp0WtYYS\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@rachel-taylor-docker"
+   },
+   "aef160e03958d5346c903dda755c07e952127ef523df5ec33bd9b24d41fe1cf4": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAE5gH1kg/MZeiF/GO222hxMerv7MBC\nn91IJG8BbYWKmqZm2za+/QDyrMZExTguYlutu77jZqbkRZEFb/LbL4Ntuw==\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp256",
+    "x-tuf-on-ci-online-uri": "awskms:arn:aws:kms:us-east-1:654654578585:key/751429f1-0aea-4bd8-b450-bb1bce6b058f"
+   },
+   "cda750ab29ce33e19ad2fdee4204ad0190b0a33f79e1c5c18a38992d576143d7": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEYTPARe9DPvvVVf7ch5fTVWXtS9FS97lh\nyZr3Pk33qRprnVB9u7BaEzvQtTYycPO7cmYW5yTOC5ZZa9p2B/v15bOK4NTU0WTT\nXTwSgKmJDh8CD/PBp386S8cwyyIp7NiR\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@whalelines"
+   },
+   "f2149d8b7c1ece56d87d81f27fa68b745efc841892b3acfa382ad7f611e612ec": {
+    "keytype": "ecdsa",
+    "keyval": {
+     "public": "-----BEGIN PUBLIC KEY-----\nMHYwEAYHKoZIzj0CAQYFK4EEACIDYgAEtWRLfl1pLhd5pn4gOmiCQwxE68U0+mIl\n1sU9ugeUz2aCZ9GcTjDNFE/7ZOat74ajeaFi9zmdeCi3UTYioLXNOXfbN6mxM9iQ\nGG3Z5OWYsZpeAv+5jhly2JeWUhFTuJpd\n-----END PUBLIC KEY-----\n"
+    },
+    "scheme": "ecdsa-sha2-nistp384",
+    "x-tuf-on-ci-keyowner": "@mrjoelkamp"
+   }
+  },
+  "roles": {
+   "root": {
+    "keyids": [
+     "08d6f4ca1d0be93a6ceddca15051c0aeec6b98c73e29f3a714de301042d6eeee",
+     "3ebd40525193d7628d0b9eccd4771df7297bc87519ec6f312863bb4470966bea",
+     "9c8e1be7d8d0e30656adc81ac201e05cb47a5a097d4d301fd121b77c320231c4",
+     "373d0a38247919a78cf400cf9a90abb9aa23a3c3dce1deee995fdd6a81507117",
+     "48a873aa6c4189804228590af4d48ee5ad3b76417592efdbcef2532401925669"
+    ],
+    "threshold": 3
+   },
+   "snapshot": {
+    "keyids": [
+     "aef160e03958d5346c903dda755c07e952127ef523df5ec33bd9b24d41fe1cf4"
+    ],
+    "threshold": 1,
+    "x-tuf-on-ci-expiry-period": 365,
+    "x-tuf-on-ci-signing-period": 60
+   },
+   "targets": {
+    "keyids": [
+     "f2149d8b7c1ece56d87d81f27fa68b745efc841892b3acfa382ad7f611e612ec",
+     "2ff207ae7d7b595ef69589622067ef5b6668e1a43081377d942ed8749fa919b4",
+     "6132f1f2dd14bf3e9ba1a8df4c8435a77d2fd57f4a99bbb699ae61f85907818e",
+     "cda750ab29ce33e19ad2fdee4204ad0190b0a33f79e1c5c18a38992d576143d7"
+    ],
+    "threshold": 2
+   },
+   "timestamp": {
+    "keyids": [
+     "aef160e03958d5346c903dda755c07e952127ef523df5ec33bd9b24d41fe1cf4"
+    ],
+    "threshold": 1,
+    "x-tuf-on-ci-expiry-period": 2,
+    "x-tuf-on-ci-signing-period": 1
+   }
+  },
+  "spec_version": "1.0.31",
+  "version": 1,
+  "x-tuf-on-ci-expiry-period": 365,
+  "x-tuf-on-ci-signing-period": 60
+ }
+}

internal/embed/root.go

@@ -1,13 +1,63 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package embed
 
 import (
 	_ "embed"
+	"fmt"
 )
 
 //go:embed embedded-roots/1.root-dev.json
-var DevRoot []byte
+var devRoot []byte
 
 //go:embed embedded-roots/1.root-staging.json
-var StagingRoot []byte
+var stagingRoot []byte
 
-var DefaultRoot = StagingRoot
+//go:embed embedded-roots/1.root.json
+var prodRoot []byte
+
+var defaultRoot = prodRoot
+
+type (
+	RootName     string
+	EmbeddedRoot struct {
+		Data []byte
+		Name RootName
+	}
+)
+
+var (
+	RootDev     = EmbeddedRoot{Data: devRoot, Name: "dev"}
+	RootStaging = EmbeddedRoot{Data: stagingRoot, Name: "staging"}
+	RootProd    = EmbeddedRoot{Data: prodRoot, Name: "prod"}
+	RootDefault = EmbeddedRoot{Data: defaultRoot, Name: ""}
+)
+
+func GetRootFromName(root string) (*EmbeddedRoot, error) {
+	switch root {
+	case string(RootDev.Name):
+		return &RootDev, nil
+	case string(RootStaging.Name):
+		return &RootStaging, nil
+	case string(RootProd.Name):
+		return &RootProd, nil
+	case string(RootDefault.Name):
+		return &RootDefault, nil
+	default:
+		return nil, fmt.Errorf("invalid tuf root: %s", root)
+	}
+}

internal/git/git.go

@@ -0,0 +1,176 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package git
+
+import (
+	"archive/tar"
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"os/exec"
+
+	"github.com/go-git/go-git/v5"
+	"github.com/go-git/go-git/v5/config"
+	"github.com/go-git/go-git/v5/plumbing"
+)
+
+// GitCommand is the path to the git binary, overridden in tests to check behavior when git is not installed.
+var GitCommand = "git"
+
+func Clone(ctx context.Context, gitRepo string, gitCommit string, targetDir string) error {
+	const localBranch = "FETCH_HEAD"
+
+	repo, err := git.PlainInit(targetDir, false)
+	if err != nil {
+		return fmt.Errorf("failed to init: %w", err)
+	}
+
+	remote, err := repo.CreateRemote(&config.RemoteConfig{
+		Name: "origin",
+		URLs: []string{gitRepo},
+		Fetch: []config.RefSpec{
+			config.RefSpec(fmt.Sprintf("%s:%s", gitCommit, localBranch)),
+		},
+	})
+	if err != nil {
+		return fmt.Errorf("failed to add remote: %w", err)
+	}
+
+	err = remote.FetchContext(ctx, &git.FetchOptions{
+		Depth: 1,
+	})
+	if err != nil {
+		return fmt.Errorf("failed to fetch: %w", err)
+	}
+
+	wt, err := repo.Worktree()
+	if err != nil {
+		return fmt.Errorf("failed to get worktree: %w", err)
+	}
+	err = wt.Checkout(&git.CheckoutOptions{
+		Hash: plumbing.NewHash(gitCommit),
+	})
+	if err != nil {
+		return fmt.Errorf("failed to checkout: %w", err)
+	}
+
+	return nil
+}
+
+type execError struct {
+	*exec.ExitError
+	stderr []byte
+}
+
+func (e *execError) Error() string {
+	trimmed := bytes.TrimSpace(e.stderr)
+	if len(trimmed) == 0 {
+		return e.ExitError.Error()
+	}
+	return fmt.Sprintf("%s, %q", e.ExitError.Error(), string(bytes.TrimSpace(e.stderr)))
+}
+
+func (e *execError) Unwrap() error {
+	return e.ExitError
+}
+
+// Archive creates a tar archive of the files in the subdirectory given by subdir of the git repository at gitRepoDir.
+// This is accomplished by running `git archive --format=tar HEAD:subdir` in the git repository directory.
+//
+// The archive is written to the returned io.Reader. It is not necessary to close the returned reader.
+// Any error encountered while starting the command will be returned immediately.
+// Any error encountered after the command is running will be returned on the next read from the returned io.Reader.
+func Archive(ctx context.Context, gitRepoDir string, subdir string) (io.Reader, error) {
+	readPipe, writePipe := io.Pipe()
+
+	treeish := fmt.Sprintf("HEAD:%s", subdir)
+	cmd := exec.CommandContext(ctx, GitCommand, "archive", "--format=tar", treeish)
+	// run the command inside the git repo directory
+	cmd.Dir = gitRepoDir
+
+	// set the standard output to the write end of the pipe
+	cmd.Stdout = writePipe
+
+	// capture standard error so we can include it in the error message if the command fails
+	stderr := new(bytes.Buffer)
+	cmd.Stderr = stderr
+
+	err := cmd.Start()
+	if err != nil {
+		return nil, fmt.Errorf("failed to start command: %w", err)
+	}
+
+	// spawn a goroutine to wait for the command to finish and close the write pipe
+	go func() {
+		var err error // variable to hold any error
+
+		defer func() {
+			if p := recover(); p != nil {
+				// if we panic, set err to a new error wrapping the panic value
+				err = fmt.Errorf("panic: %v", p)
+			}
+
+			// send any error from the command (or the panic above) to the write pipe
+			// or nil if there was no error
+			// this will cause the error to be returned on the next read from the read pipe
+			writePipe.CloseWithError(err)
+		}()
+
+		// wait for the command to finish and capture any error
+		err = cmd.Wait()
+		if err != nil {
+			if ee, ok := err.(*exec.ExitError); ok {
+				err = &execError{ExitError: ee, stderr: stderr.Bytes()}
+			}
+		}
+	}()
+
+	return readPipe, nil
+}
+
+func TarScrub(in io.Reader, out io.Writer) error {
+	tr := tar.NewReader(in)
+	tw := tar.NewWriter(out)
+	defer tw.Flush() // note: flush instead of close to avoid the empty block at EOF
+
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		newHdr := &tar.Header{
+			Typeflag: hdr.Typeflag,
+			Name:     hdr.Name,
+			Linkname: hdr.Linkname,
+			Size:     hdr.Size,
+			Mode:     hdr.Mode,
+			Devmajor: hdr.Devmajor,
+			Devminor: hdr.Devminor,
+		}
+		if err := tw.WriteHeader(newHdr); err != nil {
+			return err
+		}
+		_, err = io.CopyN(tw, tr, hdr.Size)
+		if err != nil {
+			return err
+		}
+	}
+}

internal/git/git_test.go

@@ -0,0 +1,42 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package git
+
+import (
+	"context"
+	"os"
+	"os/exec"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestArchiveWithInvalidGitCommand(t *testing.T) {
+	originalGitCommand := GitCommand
+	GitCommand = "invalid-git-command"
+	defer func() { GitCommand = originalGitCommand }()
+
+	tempDir, err := os.MkdirTemp("", "gitrepo")
+	if err != nil {
+		t.Fatalf("failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	ctx := context.Background()
+	_, err = Archive(ctx, tempDir, "")
+	require.ErrorIs(t, err, exec.ErrNotFound)
+}

internal/test/test-signing-key.pem

@@ -0,0 +1,5 @@
+-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEIKZEqmmd++eAY3bmPoBdY6nC2wLy4da2yeVZNKCp6Oj2oAoGCCqGSM49
+AwEHoUQDQgAEZmicqYSY38DprGr42jU0V3ND0ROjzSRH1+yjsxhh0bi52Hh/DuOh
+rSq2KJ5a09lW3ybnDjljowbkof0Y1i9Oow==
+-----END EC PRIVATE KEY-----

internal/test/test.go

@@ -1,26 +1,61 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package test
 
 import (
 	"context"
+	"crypto"
+	"crypto/x509"
+	_ "embed"
+	"encoding/pem"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"net/http/httptest"
 	"os"
+	"path/filepath"
+	"strings"
 	"testing"
 
-	"github.com/docker/attest/pkg/oci"
-	"github.com/docker/attest/pkg/policy"
-	"github.com/docker/attest/pkg/signerverifier"
-	"github.com/docker/attest/pkg/tlog"
+	"github.com/docker/attest/signerverifier"
+	"github.com/docker/attest/useragent"
+	"github.com/google/go-containerregistry/pkg/registry"
 	"github.com/secure-systems-lab/go-securesystemslib/dsse"
 )
 
 const (
-	USE_MOCK_TL     = true
-	USE_MOCK_KMS    = true
-	USE_MOCK_POLICY = true
-
-	AwsRegion    = "us-east-1"
-	AwsKmsKeyArn = "arn:aws:kms:us-east-1:175142243308:alias/doi-signing" // sandbox
+	UseMockKMS                    = true
+	AWSRegion                     = "us-east-1"
+	AWSKMSKeyARN                  = "arn:aws:kms:us-east-1:175142243308:alias/doi-signing" // sandbox
+	UnsignedLinuxAMD64ImageDigest = "sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620"
+	UnsignedLinuxArm64ImageDigest = "sha256:7a76cec943853f9f7105b1976afa1bf7cd5bb6afc4e9d5852dd8da7cf81ae86e"
 )
 
+func UnsignedTestIndex(rel ...string) string {
+	rel = append(rel, "test", "testdata", "unsigned-index")
+	return filepath.Join(rel...)
+}
+
+func UnsignedTestImage(rel ...string) string {
+	rel = append(rel, "test", "testdata", "unsigned-image")
+	return filepath.Join(rel...)
+}
+
 func CreateTempDir(t *testing.T, dir, pattern string) string {
 	// Create a temporary directory for output oci layout
 	tempDir, err := os.MkdirTemp(dir, pattern)
@@ -37,34 +72,24 @@ func CreateTempDir(t *testing.T, dir, pattern string) string {
 	return tempDir
 }
 
+//go:embed test-signing-key.pem
+var signingKey []byte
+
+func GetMockSigner(_ context.Context) (dsse.SignerVerifier, error) {
+	return signerverifier.LoadKeyPair(signingKey)
+}
+
 func Setup(t *testing.T) (context.Context, dsse.SignerVerifier) {
-	var tl tlog.TL
-	if USE_MOCK_TL {
-		tl = tlog.GetMockTL()
-	} else {
-		tl = &tlog.RekorTL{}
-	}
-
-	ctx := tlog.WithTL(context.Background(), tl)
-
-	var policyEvaluator policy.PolicyEvaluator
-	if USE_MOCK_POLICY {
-		policyEvaluator = GetMockPolicy()
-	} else {
-		policyEvaluator = policy.NewRegoEvaluator(true)
-	}
-
-	ctx = policy.WithPolicyEvaluator(ctx, policyEvaluator)
-
+	ctx := context.Background()
 	var signer dsse.SignerVerifier
 	var err error
-	if USE_MOCK_KMS {
+	if UseMockKMS {
 		signer, err = GetMockSigner(ctx)
 		if err != nil {
 			t.Fatal(err)
 		}
 	} else {
-		signer, err = signerverifier.GetAWSSigner(ctx, AwsKmsKeyArn, AwsRegion)
+		signer, err = signerverifier.GetAWSSigner(ctx, AWSKMSKeyARN, AWSRegion)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -73,14 +98,30 @@ func Setup(t *testing.T) (context.Context, dsse.SignerVerifier) {
 	return ctx, signer
 }
 
-func GetMockSigner(ctx context.Context) (dsse.SignerVerifier, error) {
-	return signerverifier.GenKeyPair()
+func NewLocalRegistry(ctx context.Context, options ...registry.Option) *httptest.Server {
+	options = append(options, registry.Logger(log.New(io.Discard, "", log.LstdFlags)))
+	regHandler := registry.New(options...)
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// Check the user agent
+		ua := r.Header.Get("User-Agent")
+		userAgent := useragent.Get(ctx)
+		if !strings.HasPrefix(ua, userAgent) {
+			http.Error(w, fmt.Sprintf("expected user agent to contain %q, got %q", userAgent, ua), http.StatusForbidden)
+		}
+		regHandler.ServeHTTP(w, r)
+	}))
 }
 
-func GetMockPolicy() policy.PolicyEvaluator {
-	return &policy.MockPolicyEvaluator{
-		EvaluateFunc: func(ctx context.Context, resolver oci.AttestationResolver, policy []*policy.PolicyFile, input *policy.PolicyInput) error {
-			return nil
-		},
+func PublicKeyToPEM(pubKey crypto.PublicKey) (string, error) {
+	derBytes, err := x509.MarshalPKIXPublicKey(pubKey)
+	if err != nil {
+		return "", err
 	}
+
+	pemBlock := &pem.Block{
+		Type:  "PUBLIC KEY",
+		Bytes: derBytes,
+	}
+
+	return string(pem.EncodeToMemory(pemBlock)), nil
 }

internal/util/crypto.go

@@ -1,3 +1,19 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package util
 
 import (
@@ -5,14 +21,11 @@ import (
 	"encoding/hex"
 )
 
-func HexHashBytes(input []byte) string {
-	s256 := sha256.New()
-	s256.Write(input)
-	hashSum := s256.Sum(nil)
-	return hex.EncodeToString(hashSum)
+func SHA256Hex(input []byte) string {
+	return hex.EncodeToString(SHA256(input))
 }
 
-func S256(data []byte) []byte {
+func SHA256(data []byte) []byte {
 	h := sha256.Sum256(data)
 	return h[:]
 }

internal/util/strings.go

@@ -1,10 +0,0 @@
-package util
-
-func StringInSlice(str string, list []string) bool {
-	for _, v := range list {
-		if v == str {
-			return true
-		}
-	}
-	return false
-}

mapping/mapping.go

@@ -0,0 +1,154 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mapping
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+
+	"github.com/docker/attest/tuf"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"sigs.k8s.io/yaml"
+)
+
+const (
+	MappingFilename = "mapping.yaml"
+)
+
+func validateMappingsFile(mappings *policyMappingsFile) error {
+	var validationErrors []error
+	if mappings.Kind != "policy-mapping" {
+		validationErrors = append(validationErrors, fmt.Errorf("file is not of kind policy-mapping: %s", mappings.Kind))
+	}
+	if mappings.Version != "v1" {
+		validationErrors = append(validationErrors, fmt.Errorf("unsupported policy mapping file version: %s", mappings.Version))
+	}
+	for _, rule := range mappings.Rules {
+		if rule.Pattern == "" {
+			validationErrors = append(validationErrors, fmt.Errorf("rule missing pattern: %s", rule))
+		}
+		if rule.PolicyID == "" && rule.Replacement == "" {
+			validationErrors = append(validationErrors, fmt.Errorf("rule must have policy-id or replacement: %s", rule))
+		}
+		if rule.PolicyID != "" && rule.Replacement != "" {
+			validationErrors = append(validationErrors, fmt.Errorf("rule cannot have both policy-id and replacement: %s", rule))
+		}
+		if rule.Platforms != nil {
+			for _, platform := range rule.Platforms {
+				if platform == "" {
+					validationErrors = append(validationErrors, fmt.Errorf("rule has empty platform: %s", rule))
+				}
+			}
+		}
+	}
+	for _, policy := range mappings.Policies {
+		if policy.ID == "" {
+			validationErrors = append(validationErrors, fmt.Errorf("policy missing id: %s", policy.ID))
+		}
+		if len(policy.Files) == 0 {
+			validationErrors = append(validationErrors, fmt.Errorf("policy missing files: %v", policy))
+		}
+		for _, file := range policy.Files {
+			if file.Path == "" {
+				validationErrors = append(validationErrors, fmt.Errorf("file missing path: %s", file))
+			}
+		}
+	}
+
+	if len(validationErrors) > 0 {
+		return errors.Join(validationErrors...)
+	}
+
+	return nil
+}
+
+func parsePolicyMappingsFile(data []byte) (*PolicyMappings, error) {
+	mappings := &policyMappingsFile{}
+	err := yaml.Unmarshal(data, mappings)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal policy mapping file: %w", err)
+	}
+	err = validateMappingsFile(mappings)
+	if err != nil {
+		return nil, fmt.Errorf("invalid policy mapping file: %w", err)
+	}
+	return expandMappingFile(mappings)
+}
+
+func LoadLocalMappings(configDir string) (*PolicyMappings, error) {
+	if configDir == "" {
+		return nil, nil
+	}
+	path := filepath.Join(configDir, MappingFilename)
+	mappingFile, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read local policy mapping file %s: %w", path, err)
+	}
+	return parsePolicyMappingsFile(mappingFile)
+}
+
+func LoadTUFMappings(tufClient tuf.Downloader, localTargetsDir string) (*PolicyMappings, error) {
+	if tufClient == nil {
+		return nil, fmt.Errorf("tuf client not set")
+	}
+	filename := MappingFilename
+	file, err := tufClient.DownloadTarget(filename, filepath.Join(localTargetsDir, filename))
+	if err != nil {
+		return nil, fmt.Errorf("failed to download policy mapping file %s: %w", filename, err)
+	}
+	return parsePolicyMappingsFile(file.Data)
+}
+
+func expandMappingFile(mappingFile *policyMappingsFile) (*PolicyMappings, error) {
+	policies := make(map[string]*PolicyMapping)
+	for _, policy := range mappingFile.Policies {
+		policies[policy.ID] = policy
+	}
+
+	var rules []*PolicyRule
+	for _, rule := range mappingFile.Rules {
+		patternRegex, err := regexp.Compile(rule.Pattern)
+		if err != nil {
+			return nil, err
+		}
+		platforms := make([]*v1.Platform, 0, len(rule.Platforms))
+		for _, platform := range rule.Platforms {
+			parsedPlatform, err := v1.ParsePlatform(platform)
+			if err != nil {
+				return nil, fmt.Errorf("failed to parse platform %s: %w", platform, err)
+			}
+			platforms = append(platforms, parsedPlatform)
+		}
+
+		rules = append(rules, &PolicyRule{
+			Pattern:     patternRegex,
+			PolicyID:    rule.PolicyID,
+			Replacement: rule.Replacement,
+			Platforms:   platforms,
+		})
+	}
+
+	return &PolicyMappings{
+		Version:  mappingFile.Version,
+		Kind:     mappingFile.Kind,
+		Policies: policies,
+		Rules:    rules,
+	}, nil
+}

mapping/mapping_test.go

@@ -0,0 +1,98 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mapping
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func newMapping() *policyMappingsFile {
+	return &policyMappingsFile{
+		Version: "v1",
+		Kind:    "policy-mapping",
+		Policies: []*PolicyMapping{
+			{
+				ID: "docker-official-images",
+				Files: []PolicyMappingFile{
+					{
+						Path: "docker.io/library/alpine",
+					},
+				},
+			},
+		},
+		Rules: []*policyRuleFile{
+			{
+				Pattern:  "docker.io/library/alpine",
+				PolicyID: "docker-official-images",
+			},
+		},
+	}
+}
+
+func TestMappingsFileValidation(t *testing.T) {
+	mappings := newMapping()
+	err := validateMappingsFile(mappings)
+	require.NoError(t, err)
+
+	mappings = newMapping()
+	mappings.Kind = "not-policy-mapping"
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "file is not of kind policy-mapping: not-policy-mapping")
+
+	mappings = newMapping()
+	mappings.Version = "v2"
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "unsupported policy mapping file version: v2")
+
+	mappings = newMapping()
+	mappings.Rules[0].Pattern = ""
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "rule missing pattern")
+
+	mappings = newMapping()
+	mappings.Rules[0].PolicyID = ""
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "rule must have policy-id or replacement")
+
+	mappings = newMapping()
+	mappings.Rules[0].PolicyID = "docker-official-images"
+	mappings.Rules[0].Replacement = "docker.io/library/alpine"
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "rule cannot have both policy-id and replacement")
+
+	mappings = newMapping()
+	mappings.Policies[0].ID = ""
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "policy missing id")
+
+	mappings = newMapping()
+	mappings.Policies[0].Files = nil
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "policy missing files")
+
+	mappings = newMapping()
+	mappings.Policies[0].Files[0].Path = ""
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "file missing path")
+
+	// multiple errors
+	mappings.Policies[0].ID = ""
+	err = validateMappingsFile(mappings)
+	require.ErrorContains(t, err, "policy missing id: \nfile missing path: {}")
+}

mapping/match.go

@@ -0,0 +1,96 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mapping
+
+import (
+	"fmt"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+)
+
+type matchType string
+
+const (
+	MatchTypePolicy        matchType = "policy"
+	MatchTypeMatchNoPolicy matchType = "match_no_policy"
+	MatchTypeNoMatch       matchType = "no_match"
+)
+
+type PolicyMatch struct {
+	MatchType   matchType
+	Policy      *PolicyMapping
+	Rule        *PolicyRule
+	MatchedName string
+}
+
+func (mappings *PolicyMappings) FindPolicyMatch(imageName string, platform *v1.Platform) (*PolicyMatch, error) {
+	if mappings == nil {
+		return &PolicyMatch{MatchType: MatchTypeNoMatch, MatchedName: imageName}, nil
+	}
+	return mappings.findPolicyMatchImpl(imageName, platform, make(map[*PolicyRule]bool))
+}
+
+func (mappings *PolicyMappings) findPolicyMatchImpl(imageName string, platform *v1.Platform, matched map[*PolicyRule]bool) (*PolicyMatch, error) {
+	for _, rule := range mappings.Rules {
+		if !rule.matchesPlatform(platform) {
+			continue
+		}
+		if rule.Pattern.MatchString(imageName) {
+			switch {
+			case rule.PolicyID == "" && rule.Replacement == "":
+				return nil, fmt.Errorf("rule %s has neither policy-id nor rewrite", rule.Pattern)
+			case rule.PolicyID != "" && rule.Replacement != "":
+				return nil, fmt.Errorf("rule %s has both policy-id and rewrite", rule.Pattern)
+			case rule.PolicyID != "":
+				policy := mappings.Policies[rule.PolicyID]
+				if policy != nil {
+					return &PolicyMatch{
+						MatchType:   MatchTypePolicy,
+						Policy:      policy,
+						Rule:        rule,
+						MatchedName: imageName,
+					}, nil
+				}
+				return &PolicyMatch{
+					MatchType:   MatchTypeMatchNoPolicy,
+					Rule:        rule,
+					MatchedName: imageName,
+				}, nil
+			case rule.Replacement != "":
+				if matched[rule] {
+					return nil, fmt.Errorf("rewrite loop detected")
+				}
+				matched[rule] = true
+				imageName = rule.Pattern.ReplaceAllString(imageName, rule.Replacement)
+				return mappings.findPolicyMatchImpl(imageName, platform, matched)
+			}
+		}
+	}
+	return &PolicyMatch{MatchType: MatchTypeNoMatch}, nil
+}
+
+func (rule *PolicyRule) matchesPlatform(platform *v1.Platform) bool {
+	if len(rule.Platforms) == 0 {
+		return true
+	}
+	for i := range rule.Platforms {
+		if rule.Platforms[i].Equals(*platform) {
+			return true
+		}
+	}
+	return false
+}

mapping/match_test.go

@@ -0,0 +1,216 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mapping
+
+import (
+	"path/filepath"
+	"testing"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFindPolicyMatch(t *testing.T) {
+	defaultPlatform, err := v1.ParsePlatform("linux/amd64")
+	require.NoError(t, err)
+	testCases := []struct {
+		name               string
+		imageName          string
+		mappingDir         string
+		expectError        bool
+		expectLoadingError bool
+		expectedMatchType  matchType
+		expectedPolicyID   string
+		expectedImageName  string
+		platform           string
+	}{
+		{
+			name:       "alpine",
+			mappingDir: "doi",
+			imageName:  "docker.io/library/alpine",
+
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:       "no match",
+			mappingDir: "doi",
+			imageName:  "docker.io/something/else",
+
+			expectedMatchType: MatchTypeNoMatch,
+		},
+		{
+			name:       "match, no policy",
+			mappingDir: "local",
+			imageName:  "docker.io/library/alpine",
+
+			expectedMatchType: MatchTypeMatchNoPolicy,
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:       "simple rewrite",
+			mappingDir: "simple-rewrite",
+			imageName:  "mycoolmirror.org/library/alpine",
+
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:       "rewrite no match",
+			mappingDir: "rewrite-to-no-match",
+			imageName:  "mycoolmirror.org/library/alpine",
+
+			expectedMatchType: MatchTypeNoMatch,
+		},
+		{
+			name:       "rewrite to match, no policy",
+			mappingDir: "rewrite-to-local",
+			imageName:  "mycoolmirror.org/library/alpine",
+
+			expectedMatchType: MatchTypeMatchNoPolicy,
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:       "multiple rewrites",
+			mappingDir: "rewrite-multiple",
+			imageName:  "myevencoolermirror.org/library/alpine",
+
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:       "rewrite loop",
+			mappingDir: "rewrite-loop",
+			imageName:  "yin/alpine",
+
+			expectError: true,
+		},
+		{
+			name:              "alpine with platform",
+			mappingDir:        "doi",
+			imageName:         "docker.io/library/alpine",
+			platform:          "linux/amd64",
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:              "alpine with platform",
+			mappingDir:        "doi-platform",
+			imageName:         "docker.io/library/alpine",
+			platform:          "linux/amd64",
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:              "alpine with no matching platform",
+			mappingDir:        "doi-platform",
+			imageName:         "docker.io/library/alpine",
+			platform:          "linux/arm64",
+			expectedMatchType: MatchTypeNoMatch,
+			expectedPolicyID:  "docker-official-images",
+		},
+		{
+			name:              "alpine with platform",
+			mappingDir:        "doi-platform",
+			imageName:         "docker.io/library/alpine",
+			platform:          "linux/amd64",
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:               "alpine with invalid platform in mapping",
+			mappingDir:         "doi-platform-broken",
+			imageName:          "docker.io/library/alpine",
+			platform:           "linux/amd64",
+			expectLoadingError: true,
+		},
+		{
+			name:              "firefox with > 1 platforms in policy",
+			mappingDir:        "doi-platform",
+			imageName:         "docker.io/mozilla/firefox",
+			platform:          "linux/arm64",
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/mozilla/firefox",
+		},
+		{
+			name:              "firefox with > 1 platforms in policy (no match)",
+			mappingDir:        "doi-platform",
+			imageName:         "docker.io/mozilla/firefox",
+			platform:          "macOs/arm64",
+			expectedMatchType: MatchTypeNoMatch,
+			expectedPolicyID:  "docker-official-images",
+		},
+		{
+			name:              "rewrite and platform",
+			mappingDir:        "doi-platform",
+			imageName:         "mycoolmirror.org/library/alpine",
+			platform:          "linux/amd64",
+			expectedMatchType: MatchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:              "rewrite and platform mismatch",
+			mappingDir:        "doi-platform",
+			imageName:         "mycoolmirror.org/library/alpine",
+			platform:          "macOs/amd64",
+			expectedMatchType: MatchTypeNoMatch,
+			expectedPolicyID:  "docker-official-images",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			mappings, err := LoadLocalMappings(filepath.Join("testdata", "mappings", tc.mappingDir))
+			if tc.expectLoadingError {
+				require.Error(t, err)
+				return
+			}
+			require.NoError(t, err)
+
+			platform := defaultPlatform
+			if tc.platform != "" {
+				platform, err = v1.ParsePlatform(tc.platform)
+				require.NoError(t, err)
+			}
+			match, err := mappings.FindPolicyMatch(tc.imageName, platform)
+			if tc.expectError {
+				require.Error(t, err)
+				// TODO: check error matches expected error message
+				return
+			}
+			require.NoError(t, err)
+			assert.Equal(t, tc.expectedMatchType, match.MatchType)
+			if match.MatchType == MatchTypePolicy {
+				if assert.NotNil(t, match.Policy) {
+					assert.Equal(t, tc.expectedPolicyID, match.Policy.ID)
+				}
+			}
+			if match.MatchType == MatchTypeMatchNoPolicy || match.MatchType == MatchTypePolicy {
+				assert.Equal(t, tc.expectedImageName, match.MatchedName)
+			}
+		})
+	}
+}

mapping/testdata/mappings/doi-platform-broken/mapping.yaml

@@ -0,0 +1,11 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    platforms: ["linux/amd64/broken/platform/spec/1.0:foobar"]
+    policy-id: docker-official-images

mapping/testdata/mappings/doi-platform/mapping.yaml

@@ -0,0 +1,17 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    platforms: ["linux/amd64"]
+    policy-id: docker-official-images
+  - pattern: "^docker.io/mozilla/(.*)$"
+    platforms: ["linux/amd64", "linux/arm64"]
+    policy-id: docker-official-images
+  - pattern: "^mycoolmirror[.]org/library/(.*)$"
+    platforms: ["linux/amd64"]
+    rewrite: "docker.io/library/$1"

mapping/testdata/mappings/doi/mapping.yaml

@@ -0,0 +1,10 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images

mapping/testdata/mappings/local/mapping.yaml

@@ -0,0 +1,10 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: local-policy
+    description: Local Policy
+    files:
+      - path: local-policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images # note this policy does not exist in this file

mapping/testdata/mappings/rewrite-invalid/mapping.yaml

@@ -0,0 +1,13 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images
+  - pattern: "^mycoolmirror[.]org/library/(.*)$"
+    rewrite: "docker.io/library/$1"
+    policy-id: docker-official-images # invalid to specify both rewrite and policy-id

mapping/testdata/mappings/rewrite-loop/mapping.yaml

@@ -0,0 +1,14 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images
+  - pattern: "^yin/(.*)$"
+    rewrite: "yang/$1"
+  - pattern: "^yang/(.*)$"
+    rewrite: "yin/$1"

mapping/testdata/mappings/rewrite-multiple/mapping.yaml

@@ -0,0 +1,14 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images
+  - pattern: "^mycoolmirror[.]org/library/(.*)$"
+    rewrite: "docker.io/library/$1"
+  - pattern: "^myevencoolermirror[.]org/library/(.*)$"
+    rewrite: "mycoolmirror.org/library/$1"

mapping/testdata/mappings/rewrite-to-local/mapping.yaml

@@ -0,0 +1,12 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: local-policy
+    description: Local Policy
+    files:
+      - path: local-policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images # note this policy does not exist in this file
+  - pattern: "^mycoolmirror[.]org/library/(.*)$"
+    rewrite: "docker.io/library/$1"

mapping/testdata/mappings/rewrite-to-no-match/mapping.yaml

@@ -0,0 +1,12 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images
+  - pattern: "^mycoolmirror[.]org/library/(.*)$"
+    rewrite: "badredirect.org/$1" # no matching rule for this rewrite

mapping/testdata/mappings/simple-rewrite/mapping.yaml

@@ -0,0 +1,12 @@
+version: v1
+kind: policy-mapping
+policies:
+  - id: docker-official-images
+    description: Docker Official Images
+    files:
+      - path: doi/policy.rego
+rules:
+  - pattern: "^docker[.]io/library/(.*)$"
+    policy-id: docker-official-images
+  - pattern: "^mycoolmirror[.]org/library/(.*)$"
+    rewrite: "docker.io/library/$1"

mapping/types.go

@@ -0,0 +1,74 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mapping
+
+import (
+	"regexp"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+)
+
+type policyMappingsFile struct {
+	Version  string            `json:"version"`
+	Kind     string            `json:"kind"`
+	Policies []*PolicyMapping  `json:"policies"`
+	Rules    []*policyRuleFile `json:"rules"`
+}
+
+type policyRuleFile struct {
+	Pattern     string   `json:"pattern"`
+	Platforms   []string `json:"platforms"`
+	PolicyID    string   `json:"policy-id"`
+	Replacement string   `json:"rewrite"`
+}
+
+type PolicyMappings struct {
+	Version  string
+	Kind     string
+	Policies map[string]*PolicyMapping
+	Rules    []*PolicyRule
+}
+
+type AttestationStyle string
+
+const (
+	AttestationStyleAttached  AttestationStyle = "attached"
+	AttestationStyleReferrers AttestationStyle = "referrers"
+)
+
+type PolicyMapping struct {
+	ID           string              `json:"id"`
+	Description  string              `json:"description"`
+	Files        []PolicyMappingFile `json:"files"`
+	Attestations *AttestationConfig  `json:"attestations"`
+}
+
+type AttestationConfig struct {
+	Style AttestationStyle `json:"style"`
+	Repo  string           `json:"repo"`
+}
+
+type PolicyMappingFile struct {
+	Path string `json:"path"`
+}
+
+type PolicyRule struct {
+	Pattern     *regexp.Regexp
+	PolicyID    string
+	Replacement string
+	Platforms   []*v1.Platform
+}

mirror/README.md

@@ -0,0 +1,2 @@
+## mirror
+This package contains components to mirror TUF metadata and targets to OCI.

mirror/example_mirror_test.go

@@ -0,0 +1,170 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mirror_test
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/docker/attest/mirror"
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/tuf"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+)
+
+type TufMirrorOutput struct {
+	metadata          v1.Image
+	delegatedMetadata []*mirror.Image
+	targets           []*mirror.Image
+	delegatedTargets  []*mirror.Index
+}
+
+func ExampleNewTUFMirror() {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		panic(err)
+	}
+	tufOutputPath := filepath.Join(home, ".docker", "tuf")
+
+	// configure TUF mirror
+	metadataURI := "https://docker.github.io/tuf-staging/metadata"
+	targetsURI := "https://docker.github.io/tuf-staging/targets"
+	ctx := context.Background()
+	m, err := mirror.NewTUFMirror(ctx, tuf.DockerTUFRootStaging.Data, tufOutputPath, metadataURI, targetsURI, tuf.NewMockVersionChecker())
+	if err != nil {
+		panic(err)
+	}
+
+	// create metadata manifest
+	metadataManifest, err := m.GetMetadataManifest(metadataURI)
+	if err != nil {
+		panic(err)
+	}
+	// create delegated targets metadata manifests
+	delegatedMetadata, err := m.GetDelegatedMetadataMirrors()
+	if err != nil {
+		panic(err)
+	}
+
+	// create targets manifest
+	targets, err := m.GetTUFTargetMirrors()
+	if err != nil {
+		panic(err)
+	}
+	// create delegated targets manifests
+	delegatedTargets, err := m.GetDelegatedTargetMirrors()
+	if err != nil {
+		panic(err)
+	}
+
+	mirrorOutput := &TufMirrorOutput{
+		metadata:          metadataManifest,
+		delegatedMetadata: delegatedMetadata,
+		targets:           targets,
+		delegatedTargets:  delegatedTargets,
+	}
+
+	// push metadata and targets to registry (optional)
+	err = mirrorToRegistry(ctx, mirrorOutput)
+	if err != nil {
+		panic(err)
+	}
+
+	// save metadata and targets to local directory (optional)
+	mirrorOutputPath := filepath.Join(home, ".docker", "tuf", "mirror")
+	err = mirrorToLocal(mirrorOutput, mirrorOutputPath)
+	if err != nil {
+		panic(err)
+	}
+}
+
+func mirrorToRegistry(ctx context.Context, o *TufMirrorOutput) error {
+	// push metadata to registry
+	metadataRepo := "registry-1.docker.io/docker/tuf-metadata:latest"
+	err := oci.PushImageToRegistry(ctx, o.metadata, metadataRepo)
+	if err != nil {
+		return err
+	}
+	// push delegated metadata to registry
+	for _, metadata := range o.delegatedMetadata {
+		repo, _, ok := strings.Cut(metadataRepo, ":")
+		if !ok {
+			return fmt.Errorf("failed to get repo without tag: %s", metadataRepo)
+		}
+		imageName := fmt.Sprintf("%s:%s", repo, metadata.Tag)
+		err = oci.PushImageToRegistry(ctx, metadata.Image, imageName)
+		if err != nil {
+			return err
+		}
+	}
+
+	// push top-level targets to registry
+	targetsRepo := "registry-1.docker.io/docker/tuf-targets"
+	for _, target := range o.targets {
+		imageName := fmt.Sprintf("%s:%s", targetsRepo, target.Tag)
+		err = oci.PushImageToRegistry(ctx, target.Image, imageName)
+		if err != nil {
+			return err
+		}
+	}
+	// push delegated targets to registry
+	for _, target := range o.delegatedTargets {
+		imageName := fmt.Sprintf("%s:%s", targetsRepo, target.Tag)
+		err = oci.PushIndexToRegistry(ctx, target.Index, imageName)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func mirrorToLocal(o *TufMirrorOutput, outputPath string) error {
+	// output metadata to local directory
+	err := oci.SaveImageAsOCILayout(o.metadata, outputPath)
+	if err != nil {
+		return err
+	}
+	// output delegated metadata to local directory
+	for _, metadata := range o.delegatedMetadata {
+		path := filepath.Join(outputPath, metadata.Tag)
+		err = oci.SaveImageAsOCILayout(metadata.Image, path)
+		if err != nil {
+			return err
+		}
+	}
+
+	// output top-level targets to local directory
+	for _, target := range o.targets {
+		path := filepath.Join(outputPath, target.Tag)
+		err = oci.SaveImageAsOCILayout(target.Image, path)
+		if err != nil {
+			return err
+		}
+	}
+	// output delegated targets to local directory
+	for _, target := range o.delegatedTargets {
+		path := filepath.Join(outputPath, target.Tag)
+		err = oci.SaveIndexAsOCILayout(target.Index, path)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}

mirror/metadata.go

@@ -1,9 +1,26 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package mirror
 
 import (
 	"fmt"
 	"strconv"
 
+	"github.com/docker/attest/oci"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/empty"
 	"github.com/google/go-containerregistry/pkg/v1/mutate"
@@ -16,9 +33,9 @@ import (
 // TUF root metadata
 // -----------------
 
-// GetMetadataManifest returns an image with TUF root metadata as layers
-func (m *TufMirror) GetMetadataManifest(metadataURL string) (*v1.Image, error) {
-	metadata, err := m.getTufMetadataMirror(metadataURL)
+// GetMetadataManifest returns an image with TUF root metadata as layers.
+func (m *TUFMirror) GetMetadataManifest(metadataURL string) (*oci.EmptyConfigImage, error) {
+	metadata, err := m.getMetadataMirror(metadataURL)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get metadata: %w", err)
 	}
@@ -26,19 +43,19 @@ func (m *TufMirror) GetMetadataManifest(metadataURL string) (*v1.Image, error) {
 	if err != nil {
 		return nil, fmt.Errorf("failed to build metadata manifest: %w", err)
 	}
-	return manifest, nil
+	return &oci.EmptyConfigImage{Image: manifest}, nil
 }
 
-// getTufMetadataMirror returns a TufMetadata struct with TUF metadata as map of file names to bytes
-func (m *TufMirror) getTufMetadataMirror(metadataURL string) (*TufMetadata, error) {
-	trustedMetadata := m.TufClient.GetMetadata()
+// getMetadataMirror returns a TufMetadata struct with TUF metadata as map of file names to bytes.
+func (m *TUFMirror) getMetadataMirror(metadataURL string) (*TUFMetadata, error) {
+	trustedMetadata := m.TUFClient.GetMetadata()
 
 	rootMetadata := map[string][]byte{}
 	rootVersion := trustedMetadata.Root.Signed.Version
 	// get the previous versions of root metadata if any
 	if rootVersion != 1 {
 		var err error
-		rootMetadata, err = m.TufClient.GetPriorRoots(metadataURL)
+		rootMetadata, err = m.TUFClient.GetPriorRoots(metadataURL)
 		if err != nil {
 			return nil, fmt.Errorf("failed to get prior root metadata: %w", err)
 		}
@@ -69,7 +86,7 @@ func (m *TufMirror) getTufMetadataMirror(metadataURL string) (*TufMetadata, erro
 		snapshotVersion = strconv.FormatInt(trustedMetadata.Snapshot.Signed.Version, 10)
 		targetsVersion = strconv.FormatInt(trustedMetadata.Targets[metadata.TARGETS].Signed.Version, 10)
 	}
-	return &TufMetadata{
+	return &TUFMetadata{
 		Root:      rootMetadata,
 		Snapshot:  map[string][]byte{nameFromRole(metadata.SNAPSHOT, snapshotVersion): snapshotBytes},
 		Targets:   map[string][]byte{nameFromRole(metadata.TARGETS, targetsVersion): targetsBytes},
@@ -77,27 +94,27 @@ func (m *TufMirror) getTufMetadataMirror(metadataURL string) (*TufMetadata, erro
 	}, nil
 }
 
-// buildMetadataManifest returns an OCI image with TUF metadata as layers with annotations
-func (m *TufMirror) buildMetadataManifest(metadata *TufMetadata) (*v1.Image, error) {
+// buildMetadataManifest returns an OCI image with TUF metadata as layers with annotations.
+func (m *TUFMirror) buildMetadataManifest(metadata *TUFMetadata) (v1.Image, error) {
 	img := empty.Image
 	img = mutate.MediaType(img, types.OCIManifestSchema1)
 	img = mutate.ConfigMediaType(img, types.OCIConfigJSON)
-	for _, role := range TufRoles {
+	for _, role := range TUFRoles {
 		layers, err := m.makeRoleLayers(role, metadata)
 		if err != nil {
 			return nil, fmt.Errorf("failed to make role layer: %w", err)
 		}
-		img, err = mutate.Append(img, *layers...)
+		img, err = mutate.Append(img, layers...)
 		if err != nil {
 			return nil, fmt.Errorf("failed to append role layer to image: %w", err)
 		}
 	}
-	return &img, nil
+	return img, nil
 }
 
-// makeRoleLayers returns a list of layers for a given TUF role
-func (m *TufMirror) makeRoleLayers(role TufRole, tufMetadata *TufMetadata) (*[]mutate.Addendum, error) {
-	layers := new([]mutate.Addendum)
+// makeRoleLayers returns a list of layers for a given TUF role.
+func (m *TUFMirror) makeRoleLayers(role TUFRole, tufMetadata *TUFMetadata) ([]mutate.Addendum, error) {
+	var layers []mutate.Addendum
 	ann := map[string]string{tufFileAnnotation: ""}
 	switch role {
 	case metadata.ROOT:
@@ -108,19 +125,19 @@ func (m *TufMirror) makeRoleLayers(role TufRole, tufMetadata *TufMetadata) (*[]m
 		layers = m.annotatedMetaLayers(tufMetadata.Targets)
 	case metadata.TIMESTAMP:
 		ann[tufFileAnnotation] = fmt.Sprintf("%s.json", role)
-		*layers = append(*layers, mutate.Addendum{Layer: static.NewLayer(tufMetadata.Timestamp, tufMetadataMediaType), Annotations: ann})
+		layers = append(layers, mutate.Addendum{Layer: static.NewLayer(tufMetadata.Timestamp, tufMetadataMediaType), Annotations: ann})
 	default:
 		return nil, fmt.Errorf("unsupported TUF role: %s", role)
 	}
 	return layers, nil
 }
 
-// annotatedMetaLayers returns a list of layers with annotations for each TUF metadata file
-func (m *TufMirror) annotatedMetaLayers(meta map[string][]byte) *[]mutate.Addendum {
-	layers := new([]mutate.Addendum)
+// annotatedMetaLayers returns a list of layers with annotations for each TUF metadata file.
+func (m *TUFMirror) annotatedMetaLayers(meta map[string][]byte) []mutate.Addendum {
+	var layers []mutate.Addendum
 	for name, data := range meta {
 		ann := map[string]string{tufFileAnnotation: name}
-		*layers = append(*layers, mutate.Addendum{Layer: static.NewLayer(data, tufMetadataMediaType), Annotations: ann})
+		layers = append(layers, mutate.Addendum{Layer: static.NewLayer(data, tufMetadataMediaType), Annotations: ann})
 	}
 	return layers
 }
@@ -129,8 +146,8 @@ func (m *TufMirror) annotatedMetaLayers(meta map[string][]byte) *[]mutate.Addend
 // TUF delegated targets metadata
 // ------------------------------
 
-// GetDelegatedMetadataMirrors returns a list of mirrors (image/tag pairs) for each delegated targets role metadata
-func (m *TufMirror) GetDelegatedMetadataMirrors() ([]*MirrorImage, error) {
+// GetDelegatedMetadataMirrors returns a list of mirrors (image/tag pairs) for each delegated targets role metadata.
+func (m *TUFMirror) GetDelegatedMetadataMirrors() ([]*Image, error) {
 	// get current delegated targets metadata
 	delegatedTargets, err := m.getDelegatedTargetsMetadata()
 	if err != nil {
@@ -143,12 +160,12 @@ func (m *TufMirror) GetDelegatedMetadataMirrors() ([]*MirrorImage, error) {
 	return mirror, nil
 }
 
-// getDelegatedTargetsMetadata returns delegated targets metadata as a list of DelegatedTargetMetadata (role name and data)
-func (m *TufMirror) getDelegatedTargetsMetadata() (*[]DelegatedTargetMetadata, error) {
-	delegatedTargets := new([]DelegatedTargetMetadata)
-	md := m.TufClient.GetMetadata()
+// getDelegatedTargetsMetadata returns delegated targets metadata as a list of DelegatedTargetMetadata (role name and data).
+func (m *TUFMirror) getDelegatedTargetsMetadata() ([]DelegatedTargetMetadata, error) {
+	var delegatedTargets []DelegatedTargetMetadata
+	md := m.TUFClient.GetMetadata()
 	for _, role := range md.Targets[metadata.TARGETS].Signed.Delegations.Roles {
-		roleMetadata, err := m.TufClient.LoadDelegatedTargets(role.Name, metadata.TARGETS)
+		roleMetadata, err := m.TUFClient.LoadDelegatedTargets(role.Name, metadata.TARGETS)
 		if err != nil {
 			return nil, fmt.Errorf("failed to get delegated role metadata: %w", err)
 		}
@@ -165,15 +182,15 @@ func (m *TufMirror) getDelegatedTargetsMetadata() (*[]DelegatedTargetMetadata, e
 		if md.Root.Signed.ConsistentSnapshot {
 			version = strconv.FormatInt(meta.Version, 10)
 		}
-		*delegatedTargets = append(*delegatedTargets, DelegatedTargetMetadata{Name: role.Name, Version: version, Data: roleBytes})
+		delegatedTargets = append(delegatedTargets, DelegatedTargetMetadata{Name: role.Name, Version: version, Data: roleBytes})
 	}
 	return delegatedTargets, nil
 }
 
-// buildDelegatedMetadataManifests returns a list of mirrors (image/tag pairs) for each delegated target role metadata
-func (m *TufMirror) buildDelegatedMetadataManifests(delegated *[]DelegatedTargetMetadata) ([]*MirrorImage, error) {
-	manifests := []*MirrorImage{}
-	for _, role := range *delegated {
+// buildDelegatedMetadataManifests returns a list of mirrors (image/tag pairs) for each delegated target role metadata.
+func (m *TUFMirror) buildDelegatedMetadataManifests(delegated []DelegatedTargetMetadata) ([]*Image, error) {
+	manifests := []*Image{}
+	for _, role := range delegated {
 		img := empty.Image
 		img = mutate.MediaType(img, types.OCIManifestSchema1)
 		img = mutate.ConfigMediaType(img, types.OCIConfigJSON)
@@ -183,7 +200,7 @@ func (m *TufMirror) buildDelegatedMetadataManifests(delegated *[]DelegatedTarget
 		if err != nil {
 			return nil, fmt.Errorf("failed to append delegated targets layer to image: %w", err)
 		}
-		manifests = append(manifests, &MirrorImage{Image: &img, Tag: role.Name})
+		manifests = append(manifests, &Image{Image: &oci.EmptyConfigImage{Image: img}, Tag: role.Name})
 	}
 	return manifests, nil
 }

mirror/metadata_test.go

@@ -1,6 +1,23 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package mirror
 
 import (
+	"context"
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
@@ -9,22 +26,27 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/docker/attest/internal/embed"
 	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/tuf"
 	"github.com/stretchr/testify/assert"
 	"github.com/theupdateframework/go-tuf/v2/metadata"
 )
 
+const (
+	metadataPath = "/metadata"
+	targetsPath  = "/targets"
+)
+
 func TestGetTufMetadataMirror(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "test", "testdata", "tuf", "test-repo"))))
+	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "test", "testdata", "tuf", "test-repo"))))
 	defer server.Close()
 
 	path := test.CreateTempDir(t, "", "tuf_temp")
-	m, err := NewTufMirror(embed.DevRoot, path, server.URL+"/metadata", server.URL+"/targets")
-	assert.Nil(t, err)
+	m, err := NewTUFMirror(context.Background(), tuf.DockerTUFRootDev.Data, path, server.URL+metadataPath, server.URL+targetsPath, tuf.NewMockVersionChecker())
+	assert.NoError(t, err)
 
-	tufMetadata, err := m.getTufMetadataMirror(server.URL + "/metadata")
-	assert.Nil(t, err)
+	tufMetadata, err := m.getMetadataMirror(server.URL + metadataPath)
+	assert.NoError(t, err)
 
 	// check that all roles are not empty
 	assert.Greater(t, len(tufMetadata.Root), 0)
@@ -34,20 +56,19 @@ func TestGetTufMetadataMirror(t *testing.T) {
 }
 
 func TestGetMetadataManifest(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "test", "testdata", "tuf", "test-repo"))))
+	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "test", "testdata", "tuf", "test-repo"))))
 	defer server.Close()
 
 	path := test.CreateTempDir(t, "", "tuf_temp")
-	m, err := NewTufMirror(embed.DevRoot, path, server.URL+"/metadata", server.URL+"/targets")
-	assert.Nil(t, err)
+	m, err := NewTUFMirror(context.Background(), tuf.DockerTUFRootDev.Data, path, server.URL+metadataPath, server.URL+targetsPath, tuf.NewMockVersionChecker())
+	assert.NoError(t, err)
 
-	img, err := m.GetMetadataManifest(server.URL + "/metadata")
-	assert.Nil(t, err)
+	img, err := m.GetMetadataManifest(server.URL + metadataPath)
+	assert.NoError(t, err)
 	assert.NotNil(t, img)
 
-	image := *img
-	mf, err := image.RawManifest()
-	assert.Nil(t, err)
+	mf, err := img.RawManifest()
+	assert.NoError(t, err)
 
 	type Annotations struct {
 		Annotations map[string]string `json:"annotations"`
@@ -57,7 +78,7 @@ func TestGetMetadataManifest(t *testing.T) {
 	}
 	l := &Layers{}
 	err = json.Unmarshal(mf, l)
-	assert.Nil(t, err)
+	assert.NoError(t, err)
 
 	// check that layers are annotated and use consistent snapshot naming
 	for _, layer := range l.Layers {
@@ -69,20 +90,20 @@ func TestGetMetadataManifest(t *testing.T) {
 			continue
 		}
 		_, err := strconv.Atoi(parts[0])
-		assert.Nil(t, err)
+		assert.NoError(t, err)
 	}
 }
 
 func TestGetDelegatedMetadataMirrors(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "test", "testdata", "tuf", "test-repo"))))
+	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "test", "testdata", "tuf", "test-repo"))))
 	defer server.Close()
 
 	path := test.CreateTempDir(t, "", "tuf_temp")
-	m, err := NewTufMirror(embed.DevRoot, path, server.URL+"/metadata", server.URL+"/targets")
-	assert.Nil(t, err)
+	m, err := NewTUFMirror(context.Background(), tuf.DockerTUFRootDev.Data, path, server.URL+metadataPath, server.URL+targetsPath, tuf.NewMockVersionChecker())
+	assert.NoError(t, err)
 
 	delegations, err := m.GetDelegatedMetadataMirrors()
-	assert.Nil(t, err)
+	assert.NoError(t, err)
 
 	assert.NotNil(t, delegations)
 	assert.Greater(t, len(delegations), 0)

mirror/mirror.go

@@ -0,0 +1,35 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mirror
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/docker/attest/tuf"
+)
+
+func NewTUFMirror(ctx context.Context, root []byte, tufPath, metadataURL, targetsURL string, versionChecker tuf.VersionChecker) (*TUFMirror, error) {
+	if root == nil {
+		root = tuf.DockerTUFRootDefault.Data
+	}
+	tufClient, err := tuf.NewClient(ctx, &tuf.ClientOptions{InitialRoot: root, LocalStorageDir: tufPath, MetadataSource: metadataURL, TargetsSource: targetsURL, VersionChecker: versionChecker})
+	if err != nil {
+		return nil, fmt.Errorf("failed to create TUF client: %w", err)
+	}
+	return &TUFMirror{TUFClient: tufClient, tufPath: tufPath, metadataURL: metadataURL, targetsURL: targetsURL}, nil
+}

mirror/targets.go

@@ -1,3 +1,19 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package mirror
 
 import (
@@ -5,6 +21,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/docker/attest/oci"
 	v1 "github.com/google/go-containerregistry/pkg/v1"
 	"github.com/google/go-containerregistry/pkg/v1/empty"
 	"github.com/google/go-containerregistry/pkg/v1/mutate"
@@ -13,16 +30,16 @@ import (
 	"github.com/theupdateframework/go-tuf/v2/metadata"
 )
 
-// GetTufTargetMirrors returns a list of top-level target files as MirrorImages (image with tag)
-func (m *TufMirror) GetTufTargetMirrors() ([]*MirrorImage, error) {
-	targetMirrors := []*MirrorImage{}
-	md := m.TufClient.GetMetadata()
+// GetTUFTargetMirrors returns a list of top-level target files as MirrorImages (image with tag).
+func (m *TUFMirror) GetTUFTargetMirrors() ([]*Image, error) {
+	targetMirrors := []*Image{}
+	md := m.TUFClient.GetMetadata()
 
 	// for each top-level target file, create an image with the target file as a layer
 	targets := md.Targets[metadata.TARGETS].Signed.Targets
 	for _, t := range targets {
 		// download target file
-		_, data, err := m.TufClient.DownloadTarget(t.Path, filepath.Join(m.tufPath, "download"))
+		file, err := m.TUFClient.DownloadTarget(t.Path, filepath.Join(m.tufPath, "download"))
 		if err != nil {
 			return nil, fmt.Errorf("failed to download target %s: %w", t.Path, err)
 		}
@@ -35,23 +52,23 @@ func (m *TufMirror) GetTufTargetMirrors() ([]*MirrorImage, error) {
 		if !ok {
 			return nil, fmt.Errorf("missing sha256 hash for target %s", t.Path)
 		}
-		name := strings.Join([]string{hash.String(), t.Path}, ".")
+		name := hash.String() + "." + t.Path
 		ann := map[string]string{tufFileAnnotation: name}
-		layer := mutate.Addendum{Layer: static.NewLayer(data, tufTargetMediaType), Annotations: ann}
+		layer := mutate.Addendum{Layer: static.NewLayer(file.Data, tufTargetMediaType), Annotations: ann}
 		img, err = mutate.Append(img, layer)
 		if err != nil {
 			return nil, fmt.Errorf("failed to append role layer to image: %w", err)
 		}
-		targetMirrors = append(targetMirrors, &MirrorImage{Image: &img, Tag: name})
+		targetMirrors = append(targetMirrors, &Image{Image: &oci.EmptyConfigImage{Image: img}, Tag: name})
 	}
 	return targetMirrors, nil
 }
 
 // GetDelegatedTargetMirrors returns a list of delegated target files as MirrorIndexes (image index with tag)
-// each image in the index contains a delegated target file
-func (m *TufMirror) GetDelegatedTargetMirrors() ([]*MirrorIndex, error) {
-	mirror := []*MirrorIndex{}
-	md := m.TufClient.GetMetadata()
+// each image in the index contains a delegated target file.
+func (m *TUFMirror) GetDelegatedTargetMirrors() ([]*Index, error) {
+	mirror := []*Index{}
+	md := m.TUFClient.GetMetadata()
 
 	// for each delegated role, create an image index with target files as images
 	roles := md.Targets[metadata.TARGETS].Signed.Delegations.Roles
@@ -60,7 +77,7 @@ func (m *TufMirror) GetDelegatedTargetMirrors() ([]*MirrorIndex, error) {
 		index := v1.ImageIndex(empty.Index)
 
 		// get delegated targets metadata for role
-		roleMeta, err := m.TufClient.LoadDelegatedTargets(role.Name, metadata.TARGETS)
+		roleMeta, err := m.TUFClient.LoadDelegatedTargets(role.Name, metadata.TARGETS)
 		if err != nil {
 			return nil, fmt.Errorf("failed to load delegated targets metadata: %w", err)
 		}
@@ -68,7 +85,7 @@ func (m *TufMirror) GetDelegatedTargetMirrors() ([]*MirrorIndex, error) {
 		// for each target file, create an image with the target file as a layer
 		for _, target := range roleMeta.Signed.Targets {
 			// download target file
-			_, data, err := m.TufClient.DownloadTarget(target.Path, filepath.Join(m.tufPath, "download"))
+			file, err := m.TUFClient.DownloadTarget(target.Path, filepath.Join(m.tufPath, "download"))
 			if err != nil {
 				return nil, fmt.Errorf("failed to download target %s: %w", target.Path, err)
 			}
@@ -86,16 +103,17 @@ func (m *TufMirror) GetDelegatedTargetMirrors() ([]*MirrorIndex, error) {
 			if !ok {
 				return nil, fmt.Errorf("failed to find target subdirectory [%s] in path: %s", subdir, target.Path)
 			}
-			name := strings.Join([]string{hash.String(), filename}, ".")
+			name := hash.String() + "." + filename
 			ann := map[string]string{tufFileAnnotation: name}
-			layer := mutate.Addendum{Layer: static.NewLayer(data, tufTargetMediaType), Annotations: ann}
+			layer := mutate.Addendum{Layer: static.NewLayer(file.Data, tufTargetMediaType), Annotations: ann}
 			img, err = mutate.Append(img, layer)
 			if err != nil {
 				return nil, fmt.Errorf("failed to append role layer to image: %w", err)
 			}
+			emptyConfigImage := &oci.EmptyConfigImage{Image: img}
 			// append image to index with annotation
 			index = mutate.AppendManifests(index, mutate.IndexAddendum{
-				Add: img,
+				Add: emptyConfigImage,
 				Descriptor: v1.Descriptor{
 					Annotations: map[string]string{
 						tufFileAnnotation: fmt.Sprintf("%s/%s", subdir, name),
@@ -103,7 +121,7 @@ func (m *TufMirror) GetDelegatedTargetMirrors() ([]*MirrorIndex, error) {
 				},
 			})
 		}
-		mirror = append(mirror, &MirrorIndex{Index: &index, Tag: role.Name})
+		mirror = append(mirror, &Index{Index: index, Tag: role.Name})
 	}
 	return mirror, nil
 }

mirror/targets_test.go

@@ -1,6 +1,23 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
 package mirror
 
 import (
+	"context"
 	"encoding/json"
 	"net/http"
 	"net/http/httptest"
@@ -8,8 +25,8 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/docker/attest/internal/embed"
 	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/tuf"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -22,82 +39,82 @@ type Layers struct {
 }
 
 func TestGetTufTargetsMirror(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "test", "testdata", "tuf", "test-repo"))))
+	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "test", "testdata", "tuf", "test-repo"))))
 	defer server.Close()
 
 	path := test.CreateTempDir(t, "", "tuf_temp")
-	m, err := NewTufMirror(embed.DevRoot, path, server.URL+"/metadata", server.URL+"/targets")
-	assert.Nil(t, err)
+	m, err := NewTUFMirror(context.Background(), tuf.DockerTUFRootDev.Data, path, server.URL+metadataPath, server.URL+targetsPath, tuf.NewMockVersionChecker())
+	assert.NoError(t, err)
 
-	targets, err := m.GetTufTargetMirrors()
-	assert.Nil(t, err)
+	targets, err := m.GetTUFTargetMirrors()
+	assert.NoError(t, err)
 	assert.Greater(t, len(targets), 0)
 
 	// check for image layer annotations
 	for _, target := range targets {
-		img := *target.Image
+		img := target.Image
 		mf, err := img.RawManifest()
-		assert.Nil(t, err)
+		assert.NoError(t, err)
 
 		// unmarshal manifest with annotations
 		l := &Layers{}
 		err = json.Unmarshal(mf, l)
-		assert.Nil(t, err)
+		assert.NoError(t, err)
 
 		// check that layers are annotated
 		for _, layer := range l.Layers {
 			ann, ok := layer.Annotations[tufFileAnnotation]
 			assert.True(t, ok)
 			parts := strings.Split(ann, ".")
-			// <digest>.filename.json
-			assert.Equal(t, len(parts), 3)
+			// <digest>.filename.<ext|optional>
+			assert.GreaterOrEqual(t, len(parts), 2)
 		}
 	}
 }
 
 func TestTargetDelegationMetadata(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "test", "testdata", "tuf", "test-repo"))))
+	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "test", "testdata", "tuf", "test-repo"))))
 	defer server.Close()
 
 	path := test.CreateTempDir(t, "", "tuf_temp")
-	tm, err := NewTufMirror(embed.DevRoot, path, server.URL+"/metadata", server.URL+"/targets")
-	assert.Nil(t, err)
+	tm, err := NewTUFMirror(context.Background(), tuf.DockerTUFRootDev.Data, path, server.URL+metadataPath, server.URL+targetsPath, tuf.NewMockVersionChecker())
+	assert.NoError(t, err)
 
-	targets, err := tm.TufClient.LoadDelegatedTargets("test-role", "targets")
-	assert.Nil(t, err)
+	targets, err := tm.TUFClient.LoadDelegatedTargets("test-role", "targets")
+	assert.NoError(t, err)
 	assert.Greater(t, len(targets.Signed.Targets), 0)
 }
 
 func TestGetDelegatedTargetMirrors(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "test", "testdata", "tuf", "test-repo"))))
+	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "test", "testdata", "tuf", "test-repo"))))
 	defer server.Close()
 
 	path := test.CreateTempDir(t, "", "tuf_temp")
-	m, err := NewTufMirror(embed.DevRoot, path, server.URL+"/metadata", server.URL+"/targets")
-	assert.Nil(t, err)
+	m, err := NewTUFMirror(context.Background(), tuf.DockerTUFRootDev.Data, path, server.URL+metadataPath, server.URL+targetsPath, tuf.NewMockVersionChecker())
+	assert.NoError(t, err)
 
 	mirrors, err := m.GetDelegatedTargetMirrors()
-	assert.Nil(t, err)
+	assert.NoError(t, err)
 	assert.Greater(t, len(mirrors), 0)
 
 	// check for index image annotations
 	for _, mirror := range mirrors {
-		idx := *mirror.Index
+		idx := mirror.Index
 		mf, err := idx.RawManifest()
-		assert.Nil(t, err)
+		assert.NoError(t, err)
 
 		// unmarshal manifest with annotations
 		l := &Layers{}
 		err = json.Unmarshal(mf, l)
-		assert.Nil(t, err)
+		assert.NoError(t, err)
 
 		// check that layers are annotated
 		for _, layer := range l.Layers {
 			ann, ok := layer.Annotations[tufFileAnnotation]
 			assert.True(t, ok)
 			parts := strings.Split(ann, ".")
-			// <subdir>/<digest>.filename.json
-			assert.Equal(t, len(parts), 3)
+			// <subdir>/<digest>.filename.<ext|optional>
+			assert.GreaterOrEqual(t, len(parts), 2)
 		}
 	}
 }

mirror/types.go

@@ -0,0 +1,66 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package mirror
+
+import (
+	"github.com/docker/attest/oci"
+	"github.com/docker/attest/tuf"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/theupdateframework/go-tuf/v2/metadata"
+)
+
+const (
+	DefaultMetadataURL   = "https://docker.github.io/tuf/metadata"
+	DefaultTargetsURL    = "https://docker.github.io/tuf/targets"
+	tufMetadataMediaType = "application/vnd.tuf.metadata+json"
+	tufTargetMediaType   = "application/vnd.tuf.target"
+	tufFileAnnotation    = "tuf.io/filename"
+)
+
+type TUFRole string
+
+var TUFRoles = []TUFRole{metadata.ROOT, metadata.SNAPSHOT, metadata.TARGETS, metadata.TIMESTAMP}
+
+type TUFMetadata struct {
+	Root      map[string][]byte
+	Snapshot  map[string][]byte
+	Targets   map[string][]byte
+	Timestamp []byte
+}
+
+type DelegatedTargetMetadata struct {
+	Name    string
+	Version string
+	Data    []byte
+}
+
+type Image struct {
+	Image *oci.EmptyConfigImage
+	Tag   string
+}
+
+type Index struct {
+	Index v1.ImageIndex
+	Tag   string
+}
+
+type TUFMirror struct {
+	TUFClient   *tuf.Client
+	tufPath     string
+	metadataURL string
+	targetsURL  string
+}

oci/README.md

@@ -0,0 +1,2 @@
+## oci
+This package is for generic OCI components. For attestation specific components see the `attestation` package.

oci/authn.go

@@ -0,0 +1,39 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import (
+	"io"
+
+	ecr "github.com/awslabs/amazon-ecr-credential-helper/ecr-login"
+	"github.com/google/go-containerregistry/pkg/authn"
+	"github.com/google/go-containerregistry/pkg/v1/google"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+func MultiKeychainOption() remote.Option {
+	return remote.WithAuthFromKeychain(MultiKeychainAll())
+}
+
+func MultiKeychainAll() authn.Keychain {
+	// Create a multi-keychain that will use the default Docker, Google, or ECR keychain
+	return authn.NewMultiKeychain(
+		authn.DefaultKeychain,
+		google.Keychain,
+		authn.NewKeychainFromHelper(ecr.NewECRHelper(ecr.WithLogger(io.Discard))),
+	)
+}

oci/authn_test.go

@@ -0,0 +1,49 @@
+//go:build e2e
+
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/oci"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRegistryAuth(t *testing.T) {
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+	require.NoError(t, err)
+	// test cases for ecr, gcr and dockerhub
+	testCases := []struct {
+		Image string
+	}{
+		{Image: "175142243308.dkr.ecr.us-east-1.amazonaws.com/e2e-test-image:latest"},
+		{Image: "docker/image-signer-verifier-test:latest"},
+	}
+	ctx := context.Background()
+	for _, tc := range testCases {
+		t.Run(tc.Image, func(t *testing.T) {
+			err := oci.PushIndexToRegistry(ctx, attIdx.Index, tc.Image)
+			require.NoError(t, err)
+			_, err = oci.IndexFromRemote(ctx, tc.Image)
+			require.NoError(t, err)
+		})
+	}
+}

oci/oci.go

@@ -0,0 +1,170 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/containerd/platforms"
+	"github.com/distribution/reference"
+	"github.com/docker/attest/useragent"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+	"github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/common"
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/package-url/packageurl-go"
+)
+
+// ParsePlatform parses the provided platform string or attempts to obtain
+// the platform of the current host system.
+func ParsePlatform(platformStr string) (*v1.Platform, error) {
+	if platformStr == "" {
+		cdp := platforms.Normalize(platforms.DefaultSpec())
+		if cdp.OS != "windows" {
+			cdp.OS = "linux"
+		}
+		return &v1.Platform{
+			OS:           cdp.OS,
+			Architecture: cdp.Architecture,
+			Variant:      cdp.Variant,
+		}, nil
+	}
+	return v1.ParsePlatform(platformStr)
+}
+
+func WithOptions(ctx context.Context, platform *v1.Platform) []remote.Option {
+	// prepare options
+	options := []remote.Option{
+		MultiKeychainOption(),
+		remote.WithContext(ctx),
+		remote.WithUserAgent(useragent.Get(ctx)),
+	}
+
+	// add in platform into remote Get operation; this might conflict with an explicit digest, but we are trying anyway
+	if platform != nil {
+		options = append(options, remote.WithPlatform(*platform))
+	}
+	return options
+}
+
+func ImageDescriptor(ix *v1.IndexManifest, platform *v1.Platform) (*v1.Descriptor, error) {
+	for i := range ix.Manifests {
+		m := &ix.Manifests[i]
+		if (m.MediaType == ocispec.MediaTypeImageManifest || m.MediaType == "application/vnd.docker.distribution.manifest.v2+json") && m.Platform.Equals(*platform) {
+			return m, nil
+		}
+	}
+	return nil, fmt.Errorf("no image found for platform %v", platform)
+}
+
+func RefToPURL(named reference.Named, platform *v1.Platform) (string, bool, error) {
+	var isCanonical bool
+	var qualifiers []packageurl.Qualifier
+
+	if canonical, ok := named.(reference.Canonical); ok {
+		qualifiers = append(qualifiers, packageurl.Qualifier{
+			Key:   "digest",
+			Value: canonical.Digest().String(),
+		})
+		isCanonical = true
+	} else {
+		named = reference.TagNameOnly(named)
+	}
+
+	version := ""
+	if tagged, ok := named.(reference.Tagged); ok {
+		version = tagged.Tag()
+	}
+
+	name := reference.FamiliarName(named)
+
+	ns := ""
+	parts := strings.Split(name, "/")
+	if len(parts) > 1 {
+		ns = strings.Join(parts[:len(parts)-1], "/")
+	}
+	name = parts[len(parts)-1]
+
+	if platform != nil {
+		qualifiers = append(qualifiers, packageurl.Qualifier{
+			Key:   "platform",
+			Value: platform.String(),
+		})
+	}
+
+	p := packageurl.NewPackageURL(packageurl.TypeDocker, ns, name, version, qualifiers, "")
+	return p.ToString(), isCanonical, nil
+}
+
+func SplitDigest(digest string) (common.DigestSet, error) {
+	parts := strings.SplitN(digest, ":", 2)
+	if len(parts) != 2 {
+		return nil, fmt.Errorf("invalid digest %q", digest)
+	}
+	return common.DigestSet{
+		parts[0]: parts[1],
+	}, nil
+}
+
+func ReplaceTagInSpec(src *ImageSpec, digest v1.Hash) (*ImageSpec, error) {
+	newName, err := ReplaceTag(src.Identifier, digest)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse repo name: %w", err)
+	}
+	return &ImageSpec{
+		Identifier: newName,
+		Type:       src.Type,
+		Platform:   src.Platform,
+	}, nil
+}
+
+// so that the index tag is replaced with a tag unique to the image digest and doesn't overwrite it.
+func ReplaceTag(image string, digest v1.Hash) (string, error) {
+	if strings.HasPrefix(image, LocalPrefix) {
+		return image, nil
+	}
+	notag, err := WithoutTag(image)
+	if err != nil {
+		return "", nil
+	}
+	return fmt.Sprintf("%s:%s-%s.att", notag, digest.Algorithm, digest.Hex), nil
+}
+
+func ReplaceDigestInSpec(src *ImageSpec, digest v1.Hash) (*ImageSpec, error) {
+	newName, err := replaceDigest(src.Identifier, digest)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse repo name: %w", err)
+	}
+	return &ImageSpec{
+		Identifier: newName,
+		Type:       src.Type,
+		Platform:   src.Platform,
+	}, nil
+}
+
+func replaceDigest(image string, digest v1.Hash) (string, error) {
+	if strings.HasPrefix(image, LocalPrefix) {
+		return image, nil
+	}
+	notag, err := WithoutTag(image)
+	if err != nil {
+		return "", nil
+	}
+	return fmt.Sprintf("%s@%s:%s", notag, digest.Algorithm, digest.Hex), nil
+}

oci/oci_test.go

@@ -0,0 +1,162 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci_test
+
+import (
+	"testing"
+
+	"github.com/distribution/reference"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/oci"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRefToPurl(t *testing.T) {
+	arm, err := oci.ParsePlatform("arm64/linux")
+	require.NoError(t, err)
+	ref, err := reference.ParseNormalizedNamed("alpine")
+	require.NoError(t, err)
+	purl, canonical, err := oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/alpine@latest?platform=arm64%2Flinux", purl)
+	assert.False(t, canonical)
+	ref, err = reference.ParseNormalizedNamed("alpine:123")
+	require.NoError(t, err)
+	purl, canonical, err = oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/alpine@123?platform=arm64%2Flinux", purl)
+	assert.False(t, canonical)
+	ref, err = reference.ParseNormalizedNamed("google/alpine:123")
+	require.NoError(t, err)
+	purl, canonical, err = oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/google/alpine@123?platform=arm64%2Flinux", purl)
+	assert.False(t, canonical)
+	ref, err = reference.ParseNormalizedNamed("library/alpine:123")
+	require.NoError(t, err)
+	purl, canonical, err = oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/alpine@123?platform=arm64%2Flinux", purl)
+	assert.False(t, canonical)
+	ref, err = reference.ParseNormalizedNamed("docker.io/library/alpine:123")
+	require.NoError(t, err)
+	purl, canonical, err = oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/alpine@123?platform=arm64%2Flinux", purl)
+	assert.False(t, canonical)
+	ref, err = reference.ParseNormalizedNamed("localhost:5001/library/alpine:123")
+	require.NoError(t, err)
+	purl, canonical, err = oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/localhost%3A5001/library/alpine@123?platform=arm64%2Flinux", purl)
+	assert.False(t, canonical)
+	ref, err = reference.ParseNormalizedNamed("localhost:5001/alpine:123")
+	require.NoError(t, err)
+	purl, canonical, err = oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/localhost%3A5001/alpine@123?platform=arm64%2Flinux", purl)
+	assert.False(t, canonical)
+	ref, err = reference.ParseNormalizedNamed("localhost:5001/alpine@sha256:c5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b")
+	require.NoError(t, err)
+	purl, canonical, err = oci.RefToPURL(ref, arm)
+	assert.NoError(t, err)
+	assert.Equal(t, "pkg:docker/localhost%3A5001/alpine?digest=sha256%3Ac5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b&platform=arm64%2Flinux", purl)
+	assert.True(t, canonical)
+}
+
+// Test fix for https://github.com/docker/secure-artifacts-team-issues/issues/202
+func TestImageDigestForPlatform(t *testing.T) {
+	idx, err := layout.ImageIndexFromPath(test.UnsignedTestIndex(".."))
+	assert.NoError(t, err)
+
+	idxm, err := idx.IndexManifest()
+	assert.NoError(t, err)
+
+	idxDescriptor := idxm.Manifests[0]
+	idxDigest := idxDescriptor.Digest
+
+	mfs, err := idx.ImageIndex(idxDigest)
+	assert.NoError(t, err)
+	mfs2, err := mfs.IndexManifest()
+	assert.NoError(t, err)
+
+	p, err := oci.ParsePlatform("linux/amd64")
+	assert.NoError(t, err)
+	desc, err := oci.ImageDescriptor(mfs2, p)
+	assert.NoError(t, err)
+	digest := desc.Digest.String()
+	assert.Equal(t, test.UnsignedLinuxAMD64ImageDigest, digest)
+
+	p, err = oci.ParsePlatform("linux/arm64")
+	assert.NoError(t, err)
+	desc, err = oci.ImageDescriptor(mfs2, p)
+	assert.NoError(t, err)
+	digest = desc.Digest.String()
+	assert.Equal(t, test.UnsignedLinuxArm64ImageDigest, digest)
+}
+
+func TestWithoutTag(t *testing.T) {
+	tc := []struct {
+		name     string
+		expected string
+	}{
+		{name: "image:tag", expected: "index.docker.io/library/image"},
+		{name: "image", expected: "index.docker.io/library/image"},
+		{name: "image:sha256-digest.att", expected: "index.docker.io/library/image"},
+		{name: oci.RegistryPrefix + "image:tag", expected: oci.RegistryPrefix + "index.docker.io/library/image"},
+		{name: "image@sha256:166710df254975d4a6c4c407c315951c22753dcaa829e020a3fd5d18fff70dd2", expected: "index.docker.io/library/image"},
+		{name: oci.RegistryPrefix + "image@sha256:166710df254975d4a6c4c407c315951c22753dcaa829e020a3fd5d18fff70dd2", expected: oci.RegistryPrefix + "index.docker.io/library/image"},
+		{name: oci.RegistryPrefix + "127.0.0.1:36555/repo:latest", expected: oci.RegistryPrefix + "127.0.0.1:36555/repo"},
+	}
+	for _, c := range tc {
+		t.Run(c.name, func(t *testing.T) {
+			notag, _ := oci.WithoutTag(c.name)
+			assert.Equal(t, c.expected, notag)
+		})
+	}
+}
+
+func TestReplaceTag(t *testing.T) {
+	tc := []struct {
+		name     string
+		expected string
+	}{
+		{name: "image:tag", expected: "index.docker.io/library/image:sha256-digest.att"},
+		{name: "image", expected: "index.docker.io/library/image:sha256-digest.att"},
+		{name: "image:sha256-digest.att", expected: "index.docker.io/library/image:sha256-digest.att"},
+		{name: oci.RegistryPrefix + "image:tag", expected: oci.RegistryPrefix + "index.docker.io/library/image:sha256-digest.att"},
+		{name: "image@sha256:166710df254975d4a6c4c407c315951c22753dcaa829e020a3fd5d18fff70dd2", expected: "index.docker.io/library/image:sha256-digest.att"},
+		{name: oci.LocalPrefix + "foobar", expected: oci.LocalPrefix + "foobar"},
+		{name: oci.RegistryPrefix + "image@sha256:166710df254975d4a6c4c407c315951c22753dcaa829e020a3fd5d18fff70dd2", expected: oci.RegistryPrefix + "index.docker.io/library/image:sha256-digest.att"},
+		{name: oci.RegistryPrefix + "127.0.0.1:36555/repo:latest", expected: oci.RegistryPrefix + "127.0.0.1:36555/repo:sha256-digest.att"},
+	}
+
+	digest := v1.Hash{
+		Algorithm: "sha256",
+		Hex:       "digest",
+	}
+	for _, c := range tc {
+		t.Run(c.name, func(t *testing.T) {
+			replaced, err := oci.ReplaceTag(c.name, digest)
+			require.NoError(t, err)
+			assert.Equal(t, c.expected, replaced)
+		})
+	}
+}

oci/output.go

@@ -0,0 +1,161 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import (
+	"context"
+	"fmt"
+	"os"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+	"github.com/google/go-containerregistry/pkg/v1/mutate"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+// PushImageToRegistry pushes an image to the registry with the specified name.
+func PushImageToRegistry(ctx context.Context, image v1.Image, imageName string) error {
+	ref, err := name.ParseReference(imageName)
+	if err != nil {
+		return fmt.Errorf("Failed to parse image name '%s': %w", imageName, err)
+	}
+
+	// Push the image to the registry
+	return remote.Write(ref, image, WithOptions(ctx, nil)...)
+}
+
+// PushIndexToRegistry pushes an index to the registry with the specified name.
+func PushIndexToRegistry(ctx context.Context, index v1.ImageIndex, imageName string) error {
+	// Parse the index name
+	ref, err := name.ParseReference(imageName)
+	if err != nil {
+		return fmt.Errorf("Failed to parse image name: %w", err)
+	}
+
+	// Push the index to the registry
+	return remote.WriteIndex(ref, index, WithOptions(ctx, nil)...)
+}
+
+// SaveIndexAsOCILayout saves an image as an OCI layout to the specified path.
+func SaveImageAsOCILayout(image v1.Image, path string) error {
+	// Save the image to the local filesystem
+	err := os.MkdirAll(path, os.ModePerm)
+	if err != nil {
+		return fmt.Errorf("failed to create directory: %w", err)
+	}
+	index := empty.Index
+	l, err := layout.Write(path, index)
+	if err != nil {
+		return fmt.Errorf("failed to create index: %w", err)
+	}
+	return l.AppendImage(image)
+}
+
+// SaveIndexAsOCILayout saves an index as an OCI layout to the specified path.
+func SaveIndexAsOCILayout(image v1.ImageIndex, path string) error {
+	// Save the index to the local filesystem
+	err := os.MkdirAll(path, os.ModePerm)
+	if err != nil {
+		return fmt.Errorf("failed to create directory: %w", err)
+	}
+
+	_, err = layout.Write(path, image)
+	if err != nil {
+		return fmt.Errorf("failed to create index: %w", err)
+	}
+	return nil
+}
+
+// SaveIndex saves an index to the specified outputs.
+func SaveIndex(ctx context.Context, outputs []*ImageSpec, index v1.ImageIndex, indexName string) error {
+	// split output by comma and write or push each one
+	for _, output := range outputs {
+		if output.Type == OCI {
+			idx := v1.ImageIndex(empty.Index)
+			idx = mutate.AppendManifests(idx, mutate.IndexAddendum{
+				Add: index,
+				Descriptor: v1.Descriptor{
+					Annotations: map[string]string{
+						OCIReferenceTarget: indexName,
+					},
+				},
+			})
+			err := SaveIndexAsOCILayout(idx, output.Identifier)
+			if err != nil {
+				return fmt.Errorf("failed to write signed image: %w", err)
+			}
+		} else {
+			err := PushIndexToRegistry(ctx, index, output.Identifier)
+			if err != nil {
+				return fmt.Errorf("failed to push signed image: %w", err)
+			}
+		}
+	}
+	return nil
+}
+
+// SaveImage saves an image to the specified output.
+func SaveImage(ctx context.Context, output *ImageSpec, image v1.Image, imageName string) error {
+	if output.Type == OCI {
+		idx := v1.ImageIndex(empty.Index)
+		idx = mutate.AppendManifests(idx, mutate.IndexAddendum{
+			Add: image,
+			Descriptor: v1.Descriptor{
+				Annotations: map[string]string{
+					OCIReferenceTarget: imageName,
+				},
+			},
+		})
+		err := SaveIndexAsOCILayout(idx, output.Identifier)
+		if err != nil {
+			return fmt.Errorf("failed to write signed image: %w", err)
+		}
+	} else {
+		err := PushImageToRegistry(ctx, image, output.Identifier)
+		if err != nil {
+			return fmt.Errorf("failed to push signed image: %w", err)
+		}
+	}
+	return nil
+}
+
+// SaveImagesNoTag saves a list of images by digest to the specified outputs.
+func SaveImagesNoTag(ctx context.Context, images []v1.Image, outputs []*ImageSpec) error {
+	for _, output := range outputs {
+		// OCI layout output not supported
+		if output.Type == OCI {
+			continue
+		}
+		for _, image := range images {
+			digest, err := image.Digest()
+			if err != nil {
+				return fmt.Errorf("failed to get image digest: %w", err)
+			}
+			spec, err := ReplaceDigestInSpec(output, digest)
+			if err != nil {
+				return fmt.Errorf("failed to create image spec: %w", err)
+			}
+			err = PushImageToRegistry(ctx, image, spec.Identifier)
+			if err != nil {
+				return fmt.Errorf("failed to push image: %w", err)
+			}
+		}
+	}
+	return nil
+}

oci/output_test.go

@@ -0,0 +1,127 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci_test
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"testing"
+
+	"github.com/docker/attest/attestation"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/oci"
+	"github.com/google/go-containerregistry/pkg/registry"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSavingIndex(t *testing.T) {
+	outputLayout := test.CreateTempDir(t, "", "mirror-test")
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestIndex(".."))
+	require.NoError(t, err)
+
+	ctx := context.Background()
+	regServer := test.NewLocalRegistry(ctx)
+	defer regServer.Close()
+
+	u, err := url.Parse(regServer.URL)
+	require.NoError(t, err)
+
+	indexName := fmt.Sprintf("%s/repo:root", u.Host)
+	output, err := oci.ParseImageSpecs(indexName)
+	require.NoError(t, err)
+	err = oci.SaveIndex(ctx, output, attIdx.Index, indexName)
+	require.NoError(t, err)
+
+	ociOutput, err := oci.ParseImageSpecs(oci.LocalPrefix + outputLayout)
+	require.NoError(t, err)
+	err = oci.SaveIndex(ctx, ociOutput, attIdx.Index, indexName)
+	require.NoError(t, err)
+}
+
+func TestSavingImage(t *testing.T) {
+	outputLayout := test.CreateTempDir(t, "", "mirror-test")
+
+	img := empty.Image
+
+	ctx := context.Background()
+	regServer := test.NewLocalRegistry(ctx)
+	defer regServer.Close()
+
+	u, err := url.Parse(regServer.URL)
+	require.NoError(t, err)
+
+	indexName := fmt.Sprintf("%s/repo:root", u.Host)
+	output, err := oci.ParseImageSpec(indexName)
+	require.NoError(t, err)
+	err = oci.SaveImage(ctx, output, img, indexName)
+	require.NoError(t, err)
+
+	ociOutput, err := oci.ParseImageSpec(oci.LocalPrefix + outputLayout)
+	require.NoError(t, err)
+	err = oci.SaveImage(ctx, ociOutput, img, indexName)
+	require.NoError(t, err)
+}
+
+func TestSavingReferrers(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	opts := &attestation.SigningOptions{}
+	statement := &intoto.Statement{
+		StatementHeader: intoto.StatementHeader{
+			PredicateType: attestation.VSAPredicateType,
+		},
+	}
+
+	digest, err := v1.NewHash(test.UnsignedLinuxAMD64ImageDigest)
+	require.NoError(t, err)
+	subject := &v1.Descriptor{
+		MediaType: "application/vnd.oci.image.manifest.v1+json",
+		Digest:    digest,
+	}
+	manifest, err := attestation.NewManifest(subject)
+	require.NoError(t, err)
+	err = manifest.Add(ctx, signer, statement, opts)
+	require.NoError(t, err)
+	regServer := test.NewLocalRegistry(ctx, registry.WithReferrersSupport(true))
+	defer regServer.Close()
+
+	u, err := url.Parse(regServer.URL)
+	require.NoError(t, err)
+
+	indexName := fmt.Sprintf("%s/repo:root", u.Host)
+	output, err := oci.ParseImageSpecs(indexName)
+	require.NoError(t, err)
+	artifacts, err := manifest.BuildReferringArtifacts()
+	require.NoError(t, err)
+	err = oci.SaveImagesNoTag(ctx, artifacts, output)
+	require.NoError(t, err)
+
+	reg := &attestation.MockRegistryResolver{
+		Subject:      subject,
+		MockResolver: &attestation.MockResolver{},
+		ImageNameStr: indexName,
+	}
+	require.NoError(t, err)
+	refResolver, err := attestation.NewReferrersResolver(reg)
+	require.NoError(t, err)
+	attestations, err := refResolver.Attestations(ctx, attestation.VSAPredicateType)
+	require.NoError(t, err)
+	require.Len(t, attestations, 1)
+}

oci/registry.go

@@ -0,0 +1,80 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+// ensure RegistryImageDetailsResolver implements ImageDetailsResolver.
+var _ ImageDetailsResolver = &RegistryImageDetailsResolver{}
+
+type RegistryImageDetailsResolver struct {
+	*ImageSpec
+	descriptor *v1.Descriptor
+}
+
+func NewRegistryImageDetailsResolver(src *ImageSpec) (*RegistryImageDetailsResolver, error) {
+	return &RegistryImageDetailsResolver{
+		ImageSpec: src,
+	}, nil
+}
+
+func (r *RegistryImageDetailsResolver) ImageName(_ context.Context) (string, error) {
+	return r.Identifier, nil
+}
+
+func (r *RegistryImageDetailsResolver) ImagePlatform(_ context.Context) (*v1.Platform, error) {
+	return r.Platform, nil
+}
+
+func (r *RegistryImageDetailsResolver) ImageDescriptor(ctx context.Context) (*v1.Descriptor, error) {
+	if r.descriptor == nil {
+		subjectRef, err := name.ParseReference(r.Identifier)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse reference: %w", err)
+		}
+		options := WithOptions(ctx, r.Platform)
+		image, err := remote.Image(subjectRef, options...)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get image manifest: %w", err)
+		}
+		digest, err := image.Digest()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get image digest: %w", err)
+		}
+		size, err := image.Size()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get image size: %w", err)
+		}
+		mediaType, err := image.MediaType()
+		if err != nil {
+			return nil, fmt.Errorf("failed to get image media type: %w", err)
+		}
+		r.descriptor = &v1.Descriptor{
+			Digest:    digest,
+			Size:      size,
+			MediaType: mediaType,
+		}
+	}
+	return r.descriptor, nil
+}

oci/resolver.go

@@ -0,0 +1,29 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import (
+	"context"
+
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+)
+
+type ImageDetailsResolver interface {
+	ImageName(ctx context.Context) (string, error)
+	ImagePlatform(ctx context.Context) (*v1.Platform, error)
+	ImageDescriptor(ctx context.Context) (*v1.Descriptor, error)
+}

oci/types.go

@@ -0,0 +1,234 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+const (
+	OCIReferenceTarget            = "org.opencontainers.image.ref.name"
+	LocalPrefix                   = "oci://"
+	RegistryPrefix                = "docker://"
+	OCI                SourceType = "OCI"
+	Docker             SourceType = "Docker"
+)
+
+type (
+	SourceType string
+	NamedIndex struct {
+		Index v1.ImageIndex
+		Name  string
+	}
+)
+
+type ImageSpecOption func(*ImageSpec) error
+
+type ImageSpec struct {
+	// OCI or Docker
+	Type SourceType
+	// without oci:// or docker:// (name or path)
+	Identifier string
+	Platform   *v1.Platform
+}
+
+func IndexFromPath(path string) (*NamedIndex, error) {
+	wrapperIdx, err := layout.ImageIndexFromPath(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load image index: %w", err)
+	}
+
+	idxm, err := wrapperIdx.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get digest: %w", err)
+	}
+	imageName := idxm.Manifests[0].Annotations[OCIReferenceTarget]
+	idxDigest := idxm.Manifests[0].Digest
+
+	idx, err := wrapperIdx.ImageIndex(idxDigest)
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract ImageIndex for digest %s: %w", idxDigest.String(), err)
+	}
+	return &NamedIndex{
+		Index: idx,
+		Name:  imageName,
+	}, nil
+}
+
+func IndexFromRemote(ctx context.Context, image string) (*NamedIndex, error) {
+	ref, err := name.ParseReference(image)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse image reference %s: %w", image, err)
+	}
+
+	// Pull the image from the registry
+	idx, err := remote.Index(ref, WithOptions(ctx, nil)...)
+	if err != nil {
+		return nil, fmt.Errorf("failed to pull image %s: %w", image, err)
+	}
+	return &NamedIndex{
+		Index: idx,
+		Name:  image,
+	}, nil
+}
+
+func LoadIndex(ctx context.Context, input *ImageSpec) (*NamedIndex, error) {
+	if input.Type == OCI {
+		return IndexFromPath(input.Identifier)
+	}
+	return IndexFromRemote(ctx, input.Identifier)
+}
+
+func (i *ImageSpec) ForPlatforms(platform string) ([]*ImageSpec, error) {
+	platforms := strings.Split(platform, ",")
+	var specs []*ImageSpec
+	for _, pStr := range platforms {
+		p, err := ParsePlatform(pStr)
+		if err != nil {
+			return nil, err
+		}
+		spec := &ImageSpec{
+			Type:       i.Type,
+			Identifier: i.Identifier,
+			Platform:   p,
+		}
+		specs = append(specs, spec)
+	}
+	return specs, nil
+}
+
+func ParseImageSpec(img string, options ...ImageSpecOption) (*ImageSpec, error) {
+	img = strings.TrimSpace(img)
+	if strings.Contains(img, ",") {
+		return nil, fmt.Errorf("only one image is supported")
+	}
+	withoutPrefix := strings.TrimPrefix(strings.TrimPrefix(img, LocalPrefix), RegistryPrefix)
+	src := &ImageSpec{
+		Identifier: withoutPrefix,
+	}
+	if strings.HasPrefix(img, LocalPrefix) {
+		src.Type = OCI
+	} else {
+		src.Type = Docker
+	}
+	for _, option := range options {
+		err := option(src)
+		if err != nil {
+			return nil, err
+		}
+	}
+	if src.Platform == nil {
+		platform, err := ParsePlatform("")
+		if err != nil {
+			return nil, err
+		}
+		src.Platform = platform
+	}
+	return src, nil
+}
+
+func WithPlatform(platform string) ImageSpecOption {
+	return func(i *ImageSpec) error {
+		if strings.Contains(platform, ",") {
+			return fmt.Errorf("only one platform is supported")
+		}
+		p, err := ParsePlatform(platform)
+		if err != nil {
+			return err
+		}
+		i.Platform = p
+		return nil
+	}
+}
+
+func ParseImageSpecs(img string) ([]*ImageSpec, error) {
+	outputs := strings.Split(img, ",")
+	var sources []*ImageSpec
+	for _, output := range outputs {
+		src, err := ParseImageSpec(output)
+		if err != nil {
+			return nil, err
+		}
+		sources = append(sources, src)
+	}
+	return sources, nil
+}
+
+func WithoutTag(image string) (string, error) {
+	if strings.HasPrefix(image, LocalPrefix) {
+		return image, nil
+	}
+	prefix := ""
+	if strings.HasPrefix(image, RegistryPrefix) {
+		image = strings.TrimPrefix(image, RegistryPrefix)
+		prefix = RegistryPrefix
+	}
+	ref, err := name.ParseReference(image)
+	if err != nil {
+		return "", err
+	}
+	repo := ref.Context().Name()
+	return prefix + repo, nil
+}
+
+type EmptyConfigImage struct {
+	v1.Image
+}
+
+func (i *EmptyConfigImage) RawConfigFile() ([]byte, error) {
+	return []byte("{}"), nil
+}
+
+func (i *EmptyConfigImage) Manifest() (*v1.Manifest, error) {
+	mf, err := i.Image.Manifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get manifest: %w", err)
+	}
+	mf.Config = v1.Descriptor{
+		MediaType: "application/vnd.oci.empty.v1+json",
+		Size:      2,
+		Digest:    v1.Hash{Algorithm: "sha256", Hex: "44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a"},
+		Data:      []byte("{}"),
+	}
+	return mf, nil
+}
+
+func (i *EmptyConfigImage) RawManifest() ([]byte, error) {
+	mf, err := i.Manifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get manifest: %w", err)
+	}
+	return json.Marshal(mf)
+}
+
+func (i *EmptyConfigImage) Digest() (v1.Hash, error) {
+	mb, err := i.RawManifest()
+	if err != nil {
+		return v1.Hash{}, err
+	}
+	digest, _, err := v1.SHA256(bytes.NewReader(mb))
+	return digest, err
+}

oci/types_test.go

@@ -0,0 +1,37 @@
+/*
+   Copyright Docker attest authors
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package oci
+
+import (
+	"testing"
+
+	"github.com/docker/attest/internal/util"
+	"github.com/google/go-containerregistry/pkg/v1/empty"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEmptyConfigImageDigest(t *testing.T) {
+	empty := empty.Image
+	img := EmptyConfigImage{Image: empty}
+	mf, err := img.RawManifest()
+	require.NoError(t, err)
+	hash := util.SHA256Hex(mf)
+	digest, err := img.Digest()
+	require.NoError(t, err)
+	assert.Equal(t, digest.Hex, hash)
+}

pkg/attestation/sign.go

@@ -1,62 +0,0 @@
-package attestation
-
-import (
-	"context"
-	"fmt"
-
-	"github.com/docker/attest/internal/util"
-	"github.com/docker/attest/pkg/tlog"
-	"github.com/secure-systems-lab/go-securesystemslib/dsse"
-)
-
-// SignDSSE signs a payload with a given signer and uploads the signature to the transparency log
-func SignDSSE(ctx context.Context, payload []byte, payloadType string, signer dsse.SignerVerifier) (*Envelope, error) {
-	t := tlog.GetTL(ctx)
-
-	env := new(Envelope)
-	env.Payload = base64Encoding.EncodeToString(payload)
-	env.PayloadType = payloadType
-	encPayload := dsse.PAE(payloadType, payload)
-
-	// statement message digest
-	hash := util.S256(encPayload)
-
-	// sign message digest
-	sig, err := signer.Sign(ctx, hash)
-	if err != nil {
-		return nil, fmt.Errorf("error signing attestation: %w", err)
-	}
-
-	// get Key ID from signer
-	keyId, err := signer.KeyID()
-	if err != nil {
-		return nil, fmt.Errorf("error getting public key ID: %w", err)
-	}
-
-	// upload to TL
-	entry, err := t.UploadLogEntry(ctx, keyId, encPayload, sig, signer)
-	if err != nil {
-		return nil, fmt.Errorf("error uploading TL entry: %w", err)
-	}
-	entryObj, err := t.UnmarshalEntry(entry)
-	if err != nil {
-		return nil, fmt.Errorf("error unmarshaling tl entry: %w", err)
-	}
-
-	// add signature w/ tl extension to dsse envelope
-	env.Signatures = append(env.Signatures, Signature{
-		KeyID: keyId,
-		Sig:   base64Encoding.EncodeToString(sig),
-		Extension: Extension{
-			Kind: DockerDsseExtKind,
-			Ext: DockerDsseExtension{
-				Tl: DockerTlExtension{
-					Kind: RekorTlExtKind,
-					Data: entryObj, // transparency log entry metadata
-				},
-			},
-		},
-	})
-
-	return env, nil
-}

pkg/attestation/sign_test.go

@@ -1,147 +0,0 @@
-package attestation_test
-
-import (
-	"crypto/ecdsa"
-	"crypto/elliptic"
-	"crypto/rand"
-	"encoding/json"
-	"fmt"
-	"testing"
-	"time"
-
-	"github.com/docker/attest/internal/test"
-	"github.com/docker/attest/pkg/attestation"
-	"github.com/docker/attest/pkg/signerverifier"
-	intoto "github.com/in-toto/in-toto-golang/in_toto"
-	"github.com/stretchr/testify/assert"
-)
-
-func TestSignVerifyAttestation(t *testing.T) {
-	ctx, signer := test.Setup(t)
-	stmt := &intoto.Statement{
-		StatementHeader: intoto.StatementHeader{
-			Type:          intoto.StatementInTotoV01,
-			PredicateType: intoto.PredicateSPDX,
-		},
-		Predicate: "test",
-	}
-
-	payload, err := json.Marshal(stmt)
-	assert.NoError(t, err)
-
-	env, err := attestation.SignDSSE(ctx, payload, intoto.PayloadType, signer)
-	assert.NoError(t, err)
-
-	// marshal envelope to json to test for bugs when marshaling envelope data
-	serializedEnv, err := json.Marshal(env)
-	assert.NoError(t, err)
-	deserializedEnv := new(attestation.Envelope)
-	err = json.Unmarshal(serializedEnv, deserializedEnv)
-	assert.NoError(t, err)
-
-	// signer.Public() calls AWS API when using AWS signer, use attestation.GetPublicVerificationKey() to get key from TUF repo
-	// signer.Public() used here for test purposes
-	ecPub, ok := signer.Public().(*ecdsa.PublicKey)
-	assert.True(t, ok)
-	pem, err := signerverifier.ToPEM(ecPub)
-	assert.NoError(t, err)
-	keyId, err := signerverifier.KeyID(ecPub)
-	assert.NoError(t, err)
-
-	badKeyPriv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
-	assert.NoError(t, err)
-	badKey := &badKeyPriv.PublicKey
-	badPEM, err := signerverifier.ToPEM(badKey)
-	assert.NoError(t, err)
-
-	testCases := []struct {
-		name          string
-		keyId         string
-		pem           []byte
-		distrust      bool
-		from          time.Time
-		to            *time.Time
-		status        string
-		expectedError string
-	}{
-		{
-			name:          "all OK",
-			keyId:         keyId,
-			pem:           pem,
-			distrust:      false,
-			from:          time.Time{},
-			to:            nil,
-			status:        "active",
-			expectedError: "",
-		},
-		{
-			name:          "key not found",
-			keyId:         "someotherkey",
-			pem:           pem,
-			distrust:      false,
-			from:          time.Time{},
-			to:            nil,
-			status:        "active",
-			expectedError: fmt.Sprintf("key not found: %s", keyId),
-		},
-		{
-			name:          "key distrusted",
-			keyId:         keyId,
-			pem:           pem,
-			distrust:      true,
-			from:          time.Time{},
-			to:            nil,
-			status:        "active",
-			expectedError: "distrusted",
-		},
-		{
-			name:          "key not yet valid",
-			keyId:         keyId,
-			pem:           pem,
-			distrust:      false,
-			from:          time.Now().Add(time.Hour),
-			to:            nil,
-			status:        "active",
-			expectedError: "not yet valid",
-		},
-		{
-			name:          "key already revoked",
-			keyId:         keyId,
-			pem:           pem,
-			distrust:      false,
-			from:          time.Time{},
-			to:            new(time.Time),
-			status:        "revoked",
-			expectedError: "already revoked",
-		},
-		{
-			name:          "bad key",
-			keyId:         keyId,
-			pem:           badPEM,
-			distrust:      false,
-			from:          time.Time{},
-			to:            nil,
-			status:        "active",
-			expectedError: "signature is not valid",
-		},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			keyMeta := attestation.KeyMetadata{
-				ID:       tc.keyId,
-				PEM:      string(tc.pem),
-				Distrust: tc.distrust,
-				From:     tc.from,
-				To:       tc.to,
-				Status:   tc.status,
-			}
-			_, err = attestation.VerifyDSSE(ctx, deserializedEnv, attestation.KeysMap{tc.keyId: keyMeta})
-			if tc.expectedError != "" {
-				assert.Contains(t, err.Error(), tc.expectedError)
-			} else {
-				assert.NoError(t, err)
-			}
-		})
-	}
-}

pkg/attestation/types.go

@@ -1,35 +0,0 @@
-package attestation
-
-import "encoding/base64"
-
-const (
-	DockerDsseExtKind = "application/vnd.docker.attestation-verification.v1+json"
-	RekorTlExtKind    = "Rekor"
-)
-
-var base64Encoding = base64.StdEncoding.Strict()
-
-// the following types are needed until https://github.com/secure-systems-lab/dsse/pull/61 is merged
-type Envelope struct {
-	PayloadType string      `json:"payloadType"`
-	Payload     string      `json:"payload"`
-	Signatures  []Signature `json:"signatures"`
-}
-type Signature struct {
-	KeyID     string    `json:"keyid"`
-	Sig       string    `json:"sig"`
-	Extension Extension `json:"extension"`
-}
-type Extension struct {
-	Kind string              `json:"kind"`
-	Ext  DockerDsseExtension `json:"ext"`
-}
-
-type DockerDsseExtension struct {
-	Tl DockerTlExtension `json:"tl"`
-}
-
-type DockerTlExtension struct {
-	Kind string `json:"kind"`
-	Data any    `json:"data"`
-}

pkg/attestation/verify.go

@@ -1,134 +0,0 @@
-package attestation
-
-import (
-	"context"
-	"crypto/ecdsa"
-	"crypto/x509"
-	"encoding/base64"
-	"encoding/json"
-	"fmt"
-	"time"
-
-	"github.com/docker/attest/internal/util"
-	"github.com/docker/attest/pkg/signerverifier"
-	"github.com/docker/attest/pkg/tlog"
-	intoto "github.com/in-toto/in-toto-golang/in_toto"
-	ociv1 "github.com/opencontainers/image-spec/specs-go/v1"
-	"github.com/secure-systems-lab/go-securesystemslib/dsse"
-)
-
-type KeyMetadata struct {
-	ID            string     `json:"id"`
-	PEM           string     `json:"key"`
-	From          time.Time  `json:"from"`
-	To            *time.Time `json:"to"`
-	Status        string     `json:"status"`
-	SigningFormat string     `json:"signing-format"`
-	Distrust      bool       `json:"distrust,omitempty"`
-}
-
-type Keys []KeyMetadata
-type KeysMap map[string]KeyMetadata
-
-func VerifyDSSE(ctx context.Context, env *Envelope, keys KeysMap) ([]byte, error) {
-	// enforce payload type
-	if !ValidPayloadType(env.PayloadType) {
-		return nil, fmt.Errorf("unsupported payload type %s", env.PayloadType)
-	}
-
-	if len(env.Signatures) == 0 {
-		return nil, fmt.Errorf("no signatures found")
-	}
-
-	payload, err := base64Encoding.DecodeString(env.Payload)
-	if err != nil {
-		return nil, fmt.Errorf("error failed to decode payload: %w", err)
-	}
-
-	encPayload := dsse.PAE(env.PayloadType, payload)
-
-	// verify signatures and transparency log entry
-	for _, sig := range env.Signatures {
-		err := verifySignature(ctx, sig, encPayload, keys)
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	return payload, nil
-}
-
-func verifySignature(ctx context.Context, sig Signature, payload []byte, keys KeysMap) error {
-	t := tlog.GetTL(ctx)
-
-	if sig.Extension.Kind == "" {
-		return fmt.Errorf("error missing signature extension kind")
-	}
-	if sig.Extension.Kind != DockerDsseExtKind {
-		return fmt.Errorf("error unsupported signature extension kind: %s", sig.Extension.Kind)
-	}
-
-	// verify TL entry
-	if sig.Extension.Ext.Tl.Kind != RekorTlExtKind {
-		return fmt.Errorf("error unsupported TL extension kind: %s", sig.Extension.Ext.Tl.Kind)
-	}
-	entry := sig.Extension.Ext.Tl.Data
-	entryBytes, err := json.Marshal(entry)
-	if err != nil {
-		return fmt.Errorf("failed to marshal TL entry: %w", err)
-	}
-
-	integratedTime, err := t.VerifyLogEntry(ctx, entryBytes)
-	if err != nil {
-		return fmt.Errorf("TL entry failed verification: %w", err)
-	}
-
-	keyMeta, ok := keys[sig.KeyID]
-	if !ok {
-		return fmt.Errorf("error key not found: %s", sig.KeyID)
-	}
-
-	if keyMeta.Distrust {
-		return fmt.Errorf("key %s is distrusted", keyMeta.ID)
-	}
-
-	if integratedTime.Before(keyMeta.From) {
-		return fmt.Errorf("key %s was not yet valid at TL log time %s (key valid from %s)", keyMeta.ID, integratedTime, keyMeta.From)
-	}
-
-	if keyMeta.To != nil && !integratedTime.Before(*keyMeta.To) {
-		return fmt.Errorf("key %s was already %s at TL log time %s (key %s at %s)", keyMeta.ID, keyMeta.Status, integratedTime, keyMeta.Status, *keyMeta.To)
-	}
-
-	// TODO: this is unmarshalling with MarshalPKIXPublicKey only for us to marshal it again
-	publicKey, err := signerverifier.Parse([]byte(keyMeta.PEM))
-	if err != nil {
-		return fmt.Errorf("failed to parse public key: %w", err)
-	}
-
-	// verify TL entry payload
-	encodedPub, err := x509.MarshalPKIXPublicKey(publicKey)
-	if err != nil {
-		return fmt.Errorf("error failed to marshal public key: %w", err)
-	}
-	err = t.VerifyEntryPayload(entryBytes, payload, encodedPub)
-	if err != nil {
-		return fmt.Errorf("TL entry failed payload verification: %w", err)
-	}
-	// decode signature
-	signature, err := base64.StdEncoding.Strict().DecodeString(sig.Sig)
-	if err != nil {
-		return fmt.Errorf("error failed to decode signature: %w", err)
-	}
-	// verify payload ecdsa signature
-	ok = ecdsa.VerifyASN1(publicKey, util.S256(payload), signature)
-	if !ok {
-		return fmt.Errorf("payload signature is not valid")
-	}
-
-	return nil
-}
-
-func ValidPayloadType(payloadType string) bool {
-	return payloadType == intoto.PayloadType || payloadType == ociv1.MediaTypeDescriptor
-}

pkg/mirror/mirror.go

@@ -1,82 +0,0 @@
-package mirror
-
-import (
-	"fmt"
-	"log"
-	"os"
-
-	"github.com/docker/attest/internal/embed"
-	"github.com/docker/attest/pkg/tuf"
-	"github.com/google/go-containerregistry/pkg/authn"
-	"github.com/google/go-containerregistry/pkg/name"
-	v1 "github.com/google/go-containerregistry/pkg/v1"
-	"github.com/google/go-containerregistry/pkg/v1/empty"
-	"github.com/google/go-containerregistry/pkg/v1/layout"
-	"github.com/google/go-containerregistry/pkg/v1/remote"
-)
-
-func NewTufMirror(root []byte, tufPath, metadataURL, targetsURL string) (*TufMirror, error) {
-	if root == nil {
-		root = embed.DefaultRoot
-	}
-	tufClient, err := tuf.NewTufClient(root, tufPath, metadataURL, targetsURL)
-	if err != nil {
-		return nil, fmt.Errorf("failed to create TUF client: %w", err)
-	}
-	return &TufMirror{TufClient: tufClient, tufPath: tufPath, metadataURL: metadataURL, targetsURL: targetsURL}, nil
-}
-
-func PushToRegistry(image any, imageName string) error {
-	// Parse the image name
-	ref, err := name.ParseReference(imageName)
-	if err != nil {
-		log.Fatalf("Failed to parse image name: %v", err)
-	}
-	// Get the authenticator from the default Docker keychain
-	auth, err := authn.DefaultKeychain.Resolve(ref.Context())
-	if err != nil {
-		log.Fatalf("Failed to get authenticator: %v", err)
-	}
-	// Push the image to the registry
-	switch image := image.(type) {
-	case *v1.Image:
-		if err := remote.Write(ref, *image, remote.WithAuth(auth)); err != nil {
-			return fmt.Errorf("failed to push image %s: %w", imageName, err)
-		}
-	case *v1.ImageIndex:
-		if err := remote.WriteIndex(ref, *image, remote.WithAuth(auth)); err != nil {
-			return fmt.Errorf("failed to push image index %s: %w", imageName, err)
-		}
-	default:
-		return fmt.Errorf("unknown image type: %T", image)
-	}
-	return nil
-}
-
-func SaveAsOCILayout(image any, path string) error {
-	// Save the image to the local filesystem
-	err := os.MkdirAll(path, os.FileMode(0744))
-	if err != nil {
-		return fmt.Errorf("failed to create directory: %w", err)
-	}
-	switch image := image.(type) {
-	case *v1.Image:
-		index := empty.Index
-		l, err := layout.Write(path, index)
-		if err != nil {
-			return fmt.Errorf("failed to create index: %w", err)
-		}
-		err = l.AppendImage(*image)
-		if err != nil {
-			return fmt.Errorf("failed to append image to index: %w", err)
-		}
-	case *v1.ImageIndex:
-		_, err := layout.Write(path, *image)
-		if err != nil {
-			return fmt.Errorf("failed to create index: %w", err)
-		}
-	default:
-		return fmt.Errorf("unknown image type: %T", image)
-	}
-	return nil
-}

pkg/mirror/types.go

@@ -1,49 +0,0 @@
-package mirror
-
-import (
-	"github.com/docker/attest/pkg/tuf"
-	v1 "github.com/google/go-containerregistry/pkg/v1"
-	"github.com/theupdateframework/go-tuf/v2/metadata"
-)
-
-const (
-	DefaultMetadataURL   = "https://docker.github.io/tuf-staging/metadata"
-	DefaultTargetsURL    = "https://docker.github.io/tuf-staging/targets"
-	tufMetadataMediaType = "application/vnd.tuf.metadata+json"
-	tufTargetMediaType   = "application/vnd.tuf.target"
-	tufFileAnnotation    = "tuf.io/filename"
-)
-
-type TufRole string
-
-var TufRoles = []TufRole{metadata.ROOT, metadata.SNAPSHOT, metadata.TARGETS, metadata.TIMESTAMP}
-
-type TufMetadata struct {
-	Root      map[string][]byte
-	Snapshot  map[string][]byte
-	Targets   map[string][]byte
-	Timestamp []byte
-}
-
-type DelegatedTargetMetadata struct {
-	Name    string
-	Version string
-	Data    []byte
-}
-
-type MirrorImage struct {
-	Image *v1.Image
-	Tag   string
-}
-
-type MirrorIndex struct {
-	Index *v1.ImageIndex
-	Tag   string
-}
-
-type TufMirror struct {
-	TufClient   *tuf.TufClient
-	tufPath     string
-	metadataURL string
-	targetsURL  string
-}

pkg/oci/http.go

@@ -1,27 +0,0 @@
-package oci
-
-import (
-	"net/http"
-
-	"github.com/hashicorp/go-cleanhttp"
-)
-
-type userAgentTransporter struct {
-	ua string
-	rt http.RoundTripper
-}
-
-type Option = func(*http.Client)
-
-func (u *userAgentTransporter) RoundTrip(req *http.Request) (*http.Response, error) {
-	req.Header.Set("User-Agent", u.ua)
-
-	return u.rt.RoundTrip(req)
-}
-
-func HttpTransport() http.RoundTripper {
-	return &userAgentTransporter{
-		ua: "Docker-Client",
-		rt: cleanhttp.DefaultTransport(),
-	}
-}

pkg/oci/oci.go

@@ -1,395 +0,0 @@
-package oci
-
-import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"strings"
-
-	"github.com/containerd/containerd/platforms"
-	"github.com/distribution/reference"
-	att "github.com/docker/attest/pkg/attestation"
-	"github.com/google/go-containerregistry/pkg/authn"
-	"github.com/google/go-containerregistry/pkg/name"
-	v1 "github.com/google/go-containerregistry/pkg/v1"
-	"github.com/google/go-containerregistry/pkg/v1/layout"
-	"github.com/google/go-containerregistry/pkg/v1/remote"
-	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
-	"github.com/package-url/packageurl-go"
-	"github.com/pkg/errors"
-)
-
-// parsePlatform parses the provided platform string or attempts to obtain
-// the platform of the current host system
-func parsePlatform(platformStr string) (*v1.Platform, error) {
-	if platformStr == "" {
-		cdp := platforms.Normalize(platforms.DefaultSpec())
-		if cdp.OS != "windows" {
-			cdp.OS = "linux"
-		}
-		return &v1.Platform{
-			OS:           cdp.OS,
-			Architecture: cdp.Architecture,
-			Variant:      cdp.Variant,
-		}, nil
-	} else {
-		return v1.ParsePlatform(platformStr)
-	}
-}
-
-func attestationManifestFromOCILayout(path string, platformStr string) (*AttestationManifest, error) {
-	idx, err := layout.ImageIndexFromPath(path)
-	if err != nil {
-		return nil, fmt.Errorf("failed to load image index: %w", err)
-	}
-
-	idxm, err := idx.IndexManifest()
-	if err != nil {
-		return nil, fmt.Errorf("failed to get digest: %w", err)
-	}
-
-	idxDescriptor := idxm.Manifests[0]
-	name := idxDescriptor.Annotations["org.opencontainers.image.ref.name"]
-	idxDigest := idxDescriptor.Digest
-
-	mfs, err := idx.ImageIndex(idxDigest)
-	if err != nil {
-		return nil, fmt.Errorf("failed to extract ImageIndex for digest %s: %w", idxDigest.String(), err)
-	}
-	mfs2, err := mfs.IndexManifest()
-	if err != nil {
-		return nil, fmt.Errorf("failed to extract IndexManifest from ImageIndex: %w", err)
-	}
-	platform, err := parsePlatform(platformStr)
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse platform: %w", err)
-	}
-	var imageDigest string
-	for _, mf := range mfs2.Manifests {
-		if mf.Platform.Equals(*platform) {
-			imageDigest = mf.Digest.String()
-		}
-	}
-	for _, mf := range mfs2.Manifests {
-		if mf.Annotations[DockerReferenceType] != AttestationManifestType {
-			continue
-		}
-
-		if mf.Annotations[DockerReferenceDigest] != imageDigest {
-			continue
-		}
-
-		attestationImage, err := mfs.Image(mf.Digest)
-		if err != nil {
-			return nil, fmt.Errorf("failed to extract attestation image with digest %s: %w", mf.Digest.String(), err)
-		}
-		manifest, err := attestationImage.Manifest()
-		if err != nil {
-			return nil, fmt.Errorf("failed to get manifest: %w", err)
-		}
-		attest := &AttestationManifest{
-			Name:       name,
-			Image:      attestationImage,
-			Manifest:   manifest,
-			Descriptor: &mf,
-			Digest:     imageDigest,
-			Platform:   platform,
-		}
-		return attest, nil
-	}
-	return nil, errors.New("attestation manifest not found")
-
-}
-
-// implementation of AttestationResolver that closes over attestations from an oci layout
-type OCILayoutResolver struct {
-	Path     string
-	Platform string
-	*AttestationManifest
-}
-
-func (r *OCILayoutResolver) ImagePlatformStr() string {
-	return r.Platform
-}
-func (r *OCILayoutResolver) fetchAttestationManifest() (*AttestationManifest, error) {
-	if r.AttestationManifest == nil {
-		m, err := attestationManifestFromOCILayout(r.Path, r.Platform)
-		if err != nil {
-			return nil, fmt.Errorf("failed to get attestation manifest: %w", err)
-		}
-		r.AttestationManifest = m
-	}
-	return r.AttestationManifest, nil
-}
-
-func (r *OCILayoutResolver) Attestations(ctx context.Context, predicateType string) ([]*att.Envelope, error) {
-	if r.AttestationManifest == nil {
-		_, err := r.fetchAttestationManifest()
-		if err != nil {
-			return nil, fmt.Errorf("failed to get attestation manifest: %w", err)
-		}
-	}
-	attestationImage := r.AttestationManifest.Image
-	layers, err := attestationImage.Layers()
-	if err != nil {
-		return nil, fmt.Errorf("failed to extract layers from attestation image: %w", err)
-	}
-	var envs []*att.Envelope
-	manifest := r.AttestationManifest.Manifest
-	for i, l := range manifest.Layers {
-		if l.Annotations[InTotoPredicateType] != predicateType {
-			continue
-		}
-		layer := layers[i]
-		mt, err := layer.MediaType()
-		if err != nil {
-			return nil, fmt.Errorf("failed to get layer media type: %w", err)
-		}
-		mts := string(mt)
-		if !strings.HasSuffix(mts, "+dsse") {
-			continue
-		}
-		var env = new(att.Envelope)
-		// parse layer blob as json
-		r, err := layer.Uncompressed()
-
-		if err != nil {
-			return nil, fmt.Errorf("failed to get layer contents: %w", err)
-		}
-		defer r.Close()
-		err = json.NewDecoder(r).Decode(env)
-		if err != nil {
-			return nil, fmt.Errorf("failed to decode envelope: %w", err)
-		}
-		envs = append(envs, env)
-	}
-	return envs, nil
-}
-
-func (r *OCILayoutResolver) ImageName(ctx context.Context) (string, error) {
-	if r.AttestationManifest == nil {
-		_, err := r.fetchAttestationManifest()
-		if err != nil {
-			return "", fmt.Errorf("failed to get attestation manifest: %w", err)
-		}
-	}
-
-	return r.Name, nil
-}
-
-func (r *OCILayoutResolver) ImageDigest(ctx context.Context) (string, error) {
-	if r.AttestationManifest == nil {
-		_, err := r.fetchAttestationManifest()
-		if err != nil {
-			return "", fmt.Errorf("failed to get attestation manifest: %w", err)
-		}
-	}
-	return r.Digest, nil
-}
-
-type RegistryResolver struct {
-	Image    string
-	Platform string
-	*AttestationManifest
-}
-
-func (r *RegistryResolver) ImageName(ctx context.Context) (string, error) {
-	return r.Image, nil
-}
-
-func (r *RegistryResolver) ImagePlatformStr() string {
-	return r.Platform
-}
-
-func (r *RegistryResolver) ImageDigest(ctx context.Context) (string, error) {
-	if r.AttestationManifest == nil {
-		attest, err := FetchAttestationManifest(ctx, r.Image, r.Platform)
-		if err != nil {
-			return "", fmt.Errorf("failed to get attestation manifest: %w", err)
-		}
-		r.AttestationManifest = attest
-	}
-	return r.Digest, nil
-}
-
-func (r *RegistryResolver) Attestations(ctx context.Context, predicateType string) ([]*att.Envelope, error) {
-	if r.AttestationManifest == nil {
-		attest, err := FetchAttestationManifest(ctx, r.Image, r.Platform)
-		if err != nil {
-			return nil, fmt.Errorf("failed to get attestation manifest: %w", err)
-		}
-		r.AttestationManifest = attest
-	}
-	return ExtractEnvelopes(r.AttestationManifest, predicateType)
-}
-
-func FetchAttestationManifest(ctx context.Context, image, platformStr string) (*AttestationManifest, error) {
-	platform, err := parsePlatform(platformStr)
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse platform %s: %w", platform, err)
-	}
-
-	// we want to get to the image index, so ignoring platform for now
-	options := withOptions(ctx, nil)
-	ref, err := name.ParseReference(image)
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse reference: %w", err)
-	}
-
-	desc, err := remote.Index(ref, options...)
-	if err != nil {
-		return nil, fmt.Errorf("failed to obtain index manifest: %w", err)
-	}
-	ix, err := desc.IndexManifest()
-	if err != nil {
-		return nil, fmt.Errorf("failed to obtain index manifest: %w", err)
-	}
-	digest, err := imageDigestForPlatform(ix, platform)
-	if err != nil {
-		return nil, fmt.Errorf("failed to obtain image for platform: %w", err)
-	}
-	ref, err = name.ParseReference(fmt.Sprintf("%s@%s", ref.Context().Name(), digest))
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse attestation reference: %w", err)
-	}
-
-	attestationDigest, err := attestationDigestForDigest(ix, digest, "attestation-manifest")
-	if err != nil {
-		return nil, fmt.Errorf("failed to obtain attestation for image: %w", err)
-	}
-	ref, err = name.ParseReference(fmt.Sprintf("%s@%s", ref.Context().Name(), attestationDigest))
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse attestation reference: %w", err)
-	}
-	remoteDescriptor, err := remote.Get(ref, options...)
-	if err != nil {
-		return nil, fmt.Errorf("failed to get attestation: %w", err)
-	}
-	manifest := new(v1.Manifest)
-	err = json.Unmarshal(remoteDescriptor.Manifest, manifest)
-	if err != nil {
-		return nil, fmt.Errorf("failed to unmarshal attestation: %w", err)
-	}
-	attestationImage, err := remoteDescriptor.Image()
-	if err != nil {
-		return nil, fmt.Errorf("failed to get attestation image: %w", err)
-	}
-	attest := &AttestationManifest{
-		Name:       image,
-		Image:      attestationImage,
-		Manifest:   manifest,
-		Descriptor: &remoteDescriptor.Descriptor,
-		Digest:     digest,
-		Platform:   platform,
-	}
-	return attest, nil
-}
-
-func withOptions(ctx context.Context, platform *v1.Platform) []remote.Option {
-	// prepare options
-	options := []remote.Option{remote.WithAuthFromKeychain(authn.DefaultKeychain), remote.WithTransport(HttpTransport()), remote.WithContext(ctx)}
-
-	// add in platform into remote Get operation; this might conflict with an explicit digest, but we are trying anyway
-	if platform != nil {
-		options = append(options, remote.WithPlatform(*platform))
-	}
-	return options
-}
-
-func ExtractEnvelopes(ia *AttestationManifest, predicateType string) ([]*att.Envelope, error) {
-	manifest := ia.Manifest
-	im := ia.Image
-
-	var envs []*att.Envelope
-
-	ls, err := im.Layers()
-	if err != nil {
-		return nil, fmt.Errorf("failed to get layers: %w", err)
-	}
-	for i, l := range manifest.Layers {
-		if (strings.HasPrefix(string(l.MediaType), "application/vnd.in-toto.")) &&
-			strings.HasSuffix(string(l.MediaType), "+dsse") &&
-			l.Annotations[InTotoPredicateType] == predicateType {
-			reader, err := ls[i].Uncompressed()
-			if err != nil {
-				return nil, fmt.Errorf("failed to get layer contents: %w", err)
-			}
-			defer reader.Close()
-			var env = new(att.Envelope)
-			err = json.NewDecoder(reader).Decode(&env)
-			if err != nil {
-				return nil, fmt.Errorf("failed to decode envelope: %w", err)
-			}
-			envs = append(envs, env)
-		}
-	}
-
-	return envs, nil
-}
-
-func imageDigestForPlatform(ix *v1.IndexManifest, platform *v1.Platform) (string, error) {
-	for _, m := range ix.Manifests {
-		if m.MediaType == ocispec.MediaTypeImageManifest || m.MediaType == "application/vnd.docker.distribution.manifest.v2+json" && m.Platform.Equals(*platform) {
-			return m.Digest.String(), nil
-		}
-	}
-	return "", errors.New(fmt.Sprintf("no image found for platform %v", platform))
-}
-
-func attestationDigestForDigest(ix *v1.IndexManifest, imageDigest string, attestType string) (string, error) {
-	for _, m := range ix.Manifests {
-		if v, ok := m.Annotations["vnd.docker.reference.type"]; ok && v == attestType {
-			if d, ok := m.Annotations["vnd.docker.reference.digest"]; ok && d == imageDigest {
-				return m.Digest.String(), nil
-			}
-		}
-	}
-	return "", errors.New(fmt.Sprintf("no attestation found for image %s", imageDigest))
-}
-
-func RefToPURL(ref string, platform string) (string, bool, error) {
-	var isCanonical bool
-	named, err := reference.ParseNormalizedNamed(ref)
-	if err != nil {
-		return "", false, fmt.Errorf("failed to parse ref %q: %w", ref, err)
-	}
-	var qualifiers []packageurl.Qualifier
-
-	if canonical, ok := named.(reference.Canonical); ok {
-		qualifiers = append(qualifiers, packageurl.Qualifier{
-			Key:   "digest",
-			Value: canonical.Digest().String(),
-		})
-		isCanonical = true
-	} else {
-		named = reference.TagNameOnly(named)
-	}
-
-	version := ""
-	if tagged, ok := named.(reference.Tagged); ok {
-		version = tagged.Tag()
-	}
-
-	name := reference.FamiliarName(named)
-
-	ns := ""
-	parts := strings.Split(name, "/")
-	if len(parts) > 1 {
-		ns = strings.Join(parts[:len(parts)-1], "/")
-	}
-	name = parts[len(parts)-1]
-
-	pf, err := parsePlatform(platform)
-	if err != nil {
-		return "", false, fmt.Errorf("failed to parse platform %q: %w", platform, err)
-	}
-	if pf != nil {
-		qualifiers = append(qualifiers, packageurl.Qualifier{
-			Key:   "platform",
-			Value: pf.String(),
-		})
-	}
-
-	p := packageurl.NewPackageURL("docker", ns, name, version, qualifiers, "")
-	return p.ToString(), isCanonical, nil
-}

pkg/oci/oci_test.go

@@ -1,49 +0,0 @@
-package oci
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestRefToPurl(t *testing.T) {
-	purl, canonical, err := RefToPURL("alpine", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/alpine@latest?platform=arm64%2Flinux", purl)
-	assert.False(t, canonical)
-
-	purl, canonical, err = RefToPURL("alpine:123", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/alpine@123?platform=arm64%2Flinux", purl)
-	assert.False(t, canonical)
-
-	purl, canonical, err = RefToPURL("google/alpine:123", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/google/alpine@123?platform=arm64%2Flinux", purl)
-	assert.False(t, canonical)
-
-	purl, canonical, err = RefToPURL("library/alpine:123", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/alpine@123?platform=arm64%2Flinux", purl)
-	assert.False(t, canonical)
-
-	purl, canonical, err = RefToPURL("docker.io/library/alpine:123", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/alpine@123?platform=arm64%2Flinux", purl)
-	assert.False(t, canonical)
-
-	purl, canonical, err = RefToPURL("localhost:5001/library/alpine:123", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/localhost%3A5001/library/alpine@123?platform=arm64%2Flinux", purl)
-	assert.False(t, canonical)
-
-	purl, canonical, err = RefToPURL("localhost:5001/alpine:123", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/localhost%3A5001/alpine@123?platform=arm64%2Flinux", purl)
-	assert.False(t, canonical)
-
-	purl, canonical, err = RefToPURL("localhost:5001/alpine@sha256:c5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b", "arm64/linux")
-	assert.NoError(t, err)
-	assert.Equal(t, "pkg:docker/localhost%3A5001/alpine?digest=sha256%3Ac5b1261d6d3e43071626931fc004f70149baeba2c8ec672bd4f27761f8e1ad6b&platform=arm64%2Flinux", purl)
-	assert.True(t, canonical)
-}

pkg/oci/resolver.go

@@ -1,46 +0,0 @@
-package oci
-
-import (
-	"context"
-
-	att "github.com/docker/attest/pkg/attestation"
-	v1 "github.com/google/go-containerregistry/pkg/v1"
-)
-
-type AttestationManifest struct {
-	// attestation image details
-	Image      v1.Image
-	Manifest   *v1.Manifest
-	Descriptor *v1.Descriptor
-	// details of subect image
-	Name     string
-	Digest   string
-	Platform *v1.Platform
-}
-
-type AttestationResolver interface {
-	ImageName(ctx context.Context) (string, error)
-	ImagePlatformStr() string
-	ImageDigest(ctx context.Context) (string, error)
-	Attestations(ctx context.Context, mediaType string) ([]*att.Envelope, error)
-}
-
-type MockResolver struct {
-	Envs []*att.Envelope
-}
-
-func (r MockResolver) Attestations(ctx context.Context, mediaType string) ([]*att.Envelope, error) {
-	return r.Envs, nil
-}
-
-func (r MockResolver) ImageName(ctx context.Context) (string, error) {
-	return "library/alpine:latest", nil
-}
-
-func (r MockResolver) ImageDigest(ctx context.Context) (string, error) {
-	return "sha256:test-digest", nil
-}
-
-func (r MockResolver) ImagePlatformStr() string {
-	return "linux/amd64"
-}

pkg/oci/types.go

@@ -1,8 +0,0 @@
-package oci
-
-const (
-	DockerReferenceType     = "vnd.docker.reference.type"
-	DockerReferenceDigest   = "vnd.docker.reference.digest"
-	AttestationManifestType = "attestation-manifest"
-	InTotoPredicateType     = "in-toto.io/predicate-type"
-)

pkg/policy/evaluator.go

@@ -1,41 +0,0 @@
-package policy
-
-import (
-	"context"
-	"fmt"
-
-	"github.com/docker/attest/pkg/oci"
-)
-
-type policyEvaluatorCtxKeyType struct{}
-
-var PolicyEvaluatorCtxKey policyEvaluatorCtxKeyType
-
-// sets PolicyEvaluator in context
-func WithPolicyEvaluator(ctx context.Context, pe PolicyEvaluator) context.Context {
-	return context.WithValue(ctx, PolicyEvaluatorCtxKey, pe)
-}
-
-// gets PolicyEvaluator from context, defaults to Rego PolicyEvaluator if not set
-func GetPolicyEvaluator(ctx context.Context) (PolicyEvaluator, error) {
-	t, ok := ctx.Value(PolicyEvaluatorCtxKey).(PolicyEvaluator)
-	if !ok {
-		return nil, fmt.Errorf("no policy evaluator client set on context (set one with policy.WithPolicyEvaluator)")
-	}
-	return t, nil
-}
-
-type PolicyEvaluator interface {
-	Evaluate(ctx context.Context, resolver oci.AttestationResolver, policy []*PolicyFile, input *PolicyInput) error
-}
-
-type MockPolicyEvaluator struct {
-	EvaluateFunc func(ctx context.Context, resolver oci.AttestationResolver, policy []*PolicyFile, input *PolicyInput) error
-}
-
-func (pe *MockPolicyEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationResolver, policy []*PolicyFile, input *PolicyInput) error {
-	if pe.EvaluateFunc != nil {
-		return pe.EvaluateFunc(ctx, resolver, policy, input)
-	}
-	return nil
-}

pkg/policy/policy.go

@@ -1,203 +0,0 @@
-package policy
-
-import (
-	"context"
-	"fmt"
-	"os"
-	"path"
-	"path/filepath"
-	"strings"
-
-	"github.com/distribution/reference"
-	"github.com/docker/attest/internal/util"
-	"github.com/docker/attest/pkg/oci"
-	"github.com/docker/attest/pkg/tuf"
-
-	goyaml "gopkg.in/yaml.v3"
-)
-
-const (
-	PolicyMappingFileName = "mapping.yaml"
-)
-
-var (
-	PolicyFileNames = []string{"data.yaml", "policy.rego"}
-)
-
-type PolicyMappings struct {
-	Version  string          `json:"version"`
-	Kind     string          `json:"kind"`
-	Policies []PolicyMapping `json:"policies"`
-	Mirrors  []PolicyMirror  `json:"mirrors"`
-}
-
-type PolicyMapping struct {
-	Name        string       `json:"namespace"`
-	Location    string       `json:"location"`
-	Description string       `json:"description"`
-	Origin      PolicyOrigin `json:"origin"`
-}
-
-type PolicyMirror struct {
-	Name   string     `json:"name"`
-	Mirror MirrorSpec `json:"mirror"`
-}
-
-type MirrorSpec struct {
-	Domains []string `json:"domains"`
-	Prefix  string   `json:"prefix"`
-}
-
-type PolicyOrigin struct {
-	Name   string `json:"name"`
-	Prefix string `json:"prefix"`
-	Domain string `json:"domain"`
-}
-
-type PolicyOptions struct {
-	TufClient       tuf.TUFClient
-	LocalTargetsDir string
-	LocalPolicyDir  string
-}
-
-type PolicyInput struct {
-	Digest      string `json:"digest"`
-	Purl        string `json:"purl"`
-	IsCanonical bool   `json:"isCanonical"`
-}
-
-type PolicyFile struct {
-	Path    string
-	Content []byte
-}
-
-func resolveLocalPolicy(opts *PolicyOptions, mapping *PolicyMapping) ([]*PolicyFile, error) {
-	if opts.LocalPolicyDir == "" {
-		return nil, fmt.Errorf("local policy dir not set")
-	}
-	files := make([]*PolicyFile, 0, len(PolicyFileNames))
-	for _, filename := range PolicyFileNames {
-		filePath := path.Join(opts.LocalPolicyDir, mapping.Location, filename)
-		fileContents, err := os.ReadFile(filePath)
-		if err != nil {
-			return nil, fmt.Errorf("failed to read policy file %s: %w", filename, err)
-		}
-		files = append(files, &PolicyFile{
-			Path:    filename,
-			Content: fileContents,
-		})
-	}
-	return files, nil
-}
-
-func loadLocalMappings(opts *PolicyOptions) (*PolicyMappings, error) {
-	if opts.LocalPolicyDir == "" {
-		return nil, nil
-	}
-	mappings := &PolicyMappings{}
-	path := path.Join(opts.LocalPolicyDir, PolicyMappingFileName)
-	mappingFile, err := os.ReadFile(path)
-	if err != nil {
-		return nil, fmt.Errorf("failed to read policy mapping file %s: %w", path, err)
-	}
-	err = goyaml.Unmarshal(mappingFile, mappings)
-	if err != nil {
-		return nil, fmt.Errorf("failed to unmarshal policy mapping file %s: %w", path, err)
-	}
-	return mappings, nil
-}
-
-func resolveTufPolicy(opts *PolicyOptions, mapping *PolicyMapping) ([]*PolicyFile, error) {
-	files := make([]*PolicyFile, 0, len(PolicyFileNames))
-	for _, filename := range PolicyFileNames {
-		filePath := path.Join(mapping.Location, filename)
-		_, fileContents, err := opts.TufClient.DownloadTarget(filePath, filepath.Join(opts.LocalTargetsDir, filePath))
-		if err != nil {
-			return nil, fmt.Errorf("failed to download policy file %s: %w", filename, err)
-		}
-		files = append(files, &PolicyFile{
-			Path:    filename,
-			Content: fileContents,
-		})
-	}
-	return files, nil
-}
-
-func loadTufMappings(tufClient tuf.TUFClient, localTargetsDir string) (*PolicyMappings, error) {
-	filename := PolicyMappingFileName
-	_, fileContents, err := tufClient.DownloadTarget(filename, filepath.Join(localTargetsDir, filename))
-	if err != nil {
-		return nil, fmt.Errorf("failed to download policy file %s: %w", filename, err)
-	}
-	mappings := &PolicyMappings{}
-
-	err = goyaml.Unmarshal(fileContents, mappings)
-	if err != nil {
-		return nil, fmt.Errorf("failed to unmarshal policy mapping file %s: %w", filename, err)
-	}
-	return mappings, nil
-}
-
-func findPolicyMatch(named reference.Named, mappings *PolicyMappings) (*PolicyMapping, *PolicyMirror) {
-	if mappings != nil {
-		for _, mapping := range mappings.Policies {
-			if mapping.Origin.Domain == reference.Domain(named) &&
-				strings.HasPrefix(reference.Path(named), mapping.Origin.Prefix) {
-				return &mapping, nil
-			}
-		}
-		// now search mirrors
-		for _, mirror := range mappings.Mirrors {
-			if util.StringInSlice(reference.Domain(named), mirror.Mirror.Domains) &&
-				strings.HasPrefix(reference.Path(named), mirror.Mirror.Prefix) {
-				for _, mapping := range mappings.Policies {
-					if mapping.Name == mirror.Name {
-						return &mapping, nil
-					}
-				}
-				return nil, &mirror
-			}
-		}
-	}
-	return nil, nil
-}
-
-func ResolvePolicy(ctx context.Context, resolver oci.AttestationResolver, opts *PolicyOptions) ([]*PolicyFile, error) {
-	imageName, err := resolver.ImageName(ctx)
-	if err != nil {
-		return nil, fmt.Errorf("failed to get image name: %w", err)
-	}
-	named, err := reference.ParseNormalizedNamed(imageName)
-	if err != nil {
-		return nil, fmt.Errorf("failed to parse image name: %w", err)
-	}
-	localMappings, err := loadLocalMappings(opts)
-	if err != nil {
-		return nil, fmt.Errorf("failed to load local policy mappings: %w", err)
-	}
-	mapping, mirror := findPolicyMatch(named, localMappings)
-	if mapping != nil {
-		return resolveLocalPolicy(opts, mapping)
-	}
-	// must check tuf
-	tufMappings, err := loadTufMappings(opts.TufClient, opts.LocalTargetsDir)
-	if err != nil {
-		return nil, fmt.Errorf("failed to load tuf policy mappings: %w", err)
-	}
-
-	// it's a mirror of a tuf policy
-	if mirror != nil {
-		for _, mapping := range tufMappings.Policies {
-			if mapping.Name == mirror.Name {
-				return resolveTufPolicy(opts, &mapping)
-			}
-		}
-	}
-
-	// try to resolve a tuf policy directly
-	mapping, _ = findPolicyMatch(named, tufMappings)
-	if mapping == nil {
-		return nil, nil
-	}
-	return resolveTufPolicy(opts, mapping)
-}

pkg/policy/policy_test.go

@@ -1,110 +0,0 @@
-package policy_test
-
-import (
-	"encoding/json"
-	"os"
-	"path/filepath"
-	"testing"
-
-	"github.com/docker/attest/internal/test"
-	"github.com/docker/attest/pkg/attestation"
-	"github.com/docker/attest/pkg/oci"
-	"github.com/docker/attest/pkg/policy"
-	"github.com/docker/attest/pkg/tuf"
-	"github.com/stretchr/testify/assert"
-)
-
-func loadAttestation(t *testing.T, path string) *attestation.Envelope {
-	ex, err := os.ReadFile(path)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	var env = new(attestation.Envelope)
-	err = json.Unmarshal(ex, env)
-	if err != nil {
-		t.Fatal(err)
-	}
-	return env
-}
-
-func TestRegoEvaluator_Evaluate(t *testing.T) {
-	ctx, _ := test.Setup(t)
-
-	TestDataPath := filepath.Join("..", "..", "test", "testdata")
-	MockTufRepo := filepath.Join(TestDataPath, "local-policy")
-	ExampleAttestation := filepath.Join(TestDataPath, "example_attestation.json")
-	VSA := filepath.Join(TestDataPath, "vsa.json")
-
-	re := policy.NewRegoEvaluator(true)
-
-	defaultInput := &policy.PolicyInput{
-		Digest:      "sha256:test-digest",
-		Purl:        "test-purl",
-		IsCanonical: true,
-	}
-
-	defaultResolver := oci.MockResolver{
-		Envs: []*attestation.Envelope{loadAttestation(t, ExampleAttestation)},
-	}
-
-	vsaResolver := oci.MockResolver{
-		Envs: []*attestation.Envelope{loadAttestation(t, ExampleAttestation), loadAttestation(t, VSA)},
-	}
-
-	testCases := []struct {
-		repo          string
-		expectSuccess bool
-		input         *policy.PolicyInput
-		resolver      oci.AttestationResolver
-		policy        *policy.PolicyOptions
-	}{
-		{repo: "testdata/mock-tuf-allow", expectSuccess: true, input: defaultInput, resolver: defaultResolver},
-		{repo: "testdata/mock-tuf-deny", expectSuccess: false, input: defaultInput, resolver: defaultResolver},
-		{repo: "testdata/mock-tuf-verify-sig", expectSuccess: true, input: defaultInput, resolver: defaultResolver},
-		{repo: "testdata/mock-tuf-wrong-key", expectSuccess: false, input: defaultInput, resolver: defaultResolver},
-		{repo: MockTufRepo, expectSuccess: true, input: &policy.PolicyInput{
-			Digest:      "sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620",
-			Purl:        "pkg:docker/test-image@test?platform=linux%2Famd64",
-			IsCanonical: true,
-		}, resolver: vsaResolver},
-		{repo: MockTufRepo, expectSuccess: true, input: &policy.PolicyInput{
-			Digest:      "sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620",
-			Purl:        "pkg:docker/test-image@test?platform=linux%2Famd64",
-			IsCanonical: false,
-		}, resolver: vsaResolver},
-		// not a doi
-		{repo: MockTufRepo, expectSuccess: false, input: defaultInput, resolver: vsaResolver, policy: &policy.PolicyOptions{
-			LocalPolicyDir: "testdata/mock-tuf-deny",
-		}},
-		// digest mismatch
-		{repo: MockTufRepo, expectSuccess: false, input: &policy.PolicyInput{
-			Digest:      "sha256:test-digest-wrong",
-			Purl:        "test-purl",
-			IsCanonical: false,
-		}, resolver: vsaResolver},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.repo, func(t *testing.T) {
-			tufClient := tuf.NewMockTufClient(tc.repo, test.CreateTempDir(t, "", "tuf-dest"))
-			if tc.policy == nil {
-				tc.policy = &policy.PolicyOptions{
-					TufClient:       tufClient,
-					LocalTargetsDir: test.CreateTempDir(t, "", "tuf-targets"),
-				}
-			}
-
-			policyFiles, err := policy.ResolvePolicy(ctx, tc.resolver, tc.policy)
-			assert.NoErrorf(t, err, "failed to resolve policy")
-			err = re.Evaluate(ctx, tc.resolver, policyFiles, tc.input)
-
-			if tc.expectSuccess {
-				assert.NoErrorf(t, err, "Evaluate failed")
-			} else {
-				assert.Errorf(t, err, "Evaluate should have failed")
-			}
-		})
-	}
-
-}

pkg/policy/rego.go

@@ -1,220 +0,0 @@
-package policy
-
-import (
-	"context"
-	"encoding/json"
-	"fmt"
-	"os"
-	"path/filepath"
-
-	att "github.com/docker/attest/pkg/attestation"
-	"github.com/docker/attest/pkg/oci"
-	intoto "github.com/in-toto/in-toto-golang/in_toto"
-	"github.com/open-policy-agent/opa/ast"
-	"github.com/open-policy-agent/opa/rego"
-	"github.com/open-policy-agent/opa/storage"
-	"github.com/open-policy-agent/opa/storage/inmem"
-	"github.com/open-policy-agent/opa/tester"
-	"github.com/open-policy-agent/opa/topdown"
-	"github.com/open-policy-agent/opa/types"
-	opa "github.com/open-policy-agent/opa/util"
-	"sigs.k8s.io/yaml"
-)
-
-type regoEvaluator struct {
-	debug bool
-}
-
-func NewRegoEvaluator(debug bool) PolicyEvaluator {
-	return &regoEvaluator{
-		debug: debug,
-	}
-}
-
-func (re *regoEvaluator) Evaluate(ctx context.Context, resolver oci.AttestationResolver, files []*PolicyFile, input *PolicyInput) error {
-	var regoOpts []func(*rego.Rego)
-
-	// Create a new in-memory store
-	store := inmem.New()
-	params := storage.TransactionParams{}
-	params.Write = true
-	txn, err := store.NewTransaction(ctx, params)
-	if err != nil {
-		return err
-	}
-
-	for _, target := range files {
-		// load yaml as data (no rego opt for this!?)
-		if filepath.Ext(target.Path) == ".yaml" {
-			yamlData, err := loadYAML(target.Path, target.Content)
-			if err != nil {
-				return err
-			}
-			err = store.Write(ctx, txn, storage.AddOp, storage.Path{}, yamlData)
-			if err != nil {
-				return err
-			}
-		} else {
-			regoOpts = append(regoOpts, rego.Module(target.Path, string(target.Content)))
-		}
-	}
-
-	err = store.Commit(ctx, txn)
-	if err != nil {
-		store.Abort(ctx, txn)
-		return err
-	}
-
-	if re.debug {
-		regoOpts = append(regoOpts,
-			rego.EnablePrintStatements(true),
-			rego.PrintHook(topdown.NewPrintHook(os.Stderr)),
-			rego.Dump(os.Stderr),
-		)
-	}
-
-	regoOpts = append(regoOpts,
-		rego.Query("data.docker.allow"),
-		rego.StrictBuiltinErrors(true),
-		rego.Input(input),
-		rego.Store(store),
-	)
-	for _, custom := range RegoFunctions(resolver) {
-		regoOpts = append(regoOpts, custom.Func)
-	}
-
-	r := rego.New(regoOpts...)
-	rs, err := r.Eval(ctx)
-	if err != nil {
-		return fmt.Errorf("error from Eval: %w", err)
-	}
-
-	if !rs.Allowed() {
-		return fmt.Errorf("policy evaluation failed")
-	}
-
-	return nil
-}
-
-var dynamicObj = types.NewObject(nil, types.NewDynamicProperty(types.S, types.A))
-var arrayObj = types.NewArray(nil, dynamicObj)
-var verifyDecl = &ast.Builtin{
-	Name:             "attestations.verify_envelope",
-	Decl:             types.NewFunction(types.Args(dynamicObj, arrayObj), dynamicObj),
-	Nondeterministic: true,
-}
-var attestDecl = &ast.Builtin{
-	Name:             "attestations.attestation",
-	Decl:             types.NewFunction(types.Args(types.S), dynamicObj),
-	Nondeterministic: true,
-}
-
-func RegoFunctions(resolver oci.AttestationResolver) []*tester.Builtin {
-	return []*tester.Builtin{
-		{
-			Decl: verifyDecl,
-			Func: rego.Function2(
-				&rego.Function{
-					Name:             verifyDecl.Name,
-					Decl:             verifyDecl.Decl,
-					Memoize:          true,
-					Nondeterministic: verifyDecl.Nondeterministic,
-				},
-				verifyIntotoEnvelope),
-		},
-		{
-			Decl: attestDecl,
-			Func: rego.Function1(
-				&rego.Function{
-					Name:             attestDecl.Name,
-					Decl:             attestDecl.Decl,
-					Memoize:          true,
-					Nondeterministic: attestDecl.Nondeterministic,
-				},
-				fetchIntotoAttestations(resolver)),
-		},
-	}
-}
-
-func fetchIntotoAttestations(resolver oci.AttestationResolver) func(rego.BuiltinContext, *ast.Term) (*ast.Term, error) {
-	return func(rCtx rego.BuiltinContext, predicateTypeTerm *ast.Term) (*ast.Term, error) {
-		predicateTypeStr, ok := predicateTypeTerm.Value.(ast.String)
-		if !ok {
-			return nil, fmt.Errorf("predicateTypeTerm is not a string")
-		}
-		predicateType := string(predicateTypeStr)
-
-		envelopes, err := resolver.Attestations(rCtx.Context, predicateType)
-		if err != nil {
-			return nil, err
-		}
-
-		// Convert each envelope to an ast.Value.
-		values := make([]*ast.Term, len(envelopes))
-		for i, envelope := range envelopes {
-			value, err := ast.InterfaceToValue(envelope)
-			if err != nil {
-				return nil, err
-			}
-			values[i] = ast.NewTerm(value)
-		}
-
-		// Wrap the values in an ast.Array and convert it to an ast.Term.
-		array := ast.NewTerm(ast.NewArray(values...))
-
-		return array, nil
-	}
-}
-func verifyIntotoEnvelope(rCtx rego.BuiltinContext, envTerm, keysTerm *ast.Term) (*ast.Term, error) {
-	env := new(att.Envelope)
-	var keys att.Keys
-	err := ast.As(envTerm.Value, env)
-	if err != nil {
-		return nil, fmt.Errorf("failed to cast envelope: %w", err)
-	}
-	err = ast.As(keysTerm.Value, &keys)
-	if err != nil {
-		return nil, fmt.Errorf("failed to cast keys: %w", err)
-	}
-	keysmap := make(map[string]att.KeyMetadata, len(keys))
-	for _, key := range keys {
-		keysmap[key.ID] = key
-	}
-	payload, err := att.VerifyDSSE(rCtx.Context, env, keysmap)
-	if err != nil {
-		return nil, err
-	}
-
-	statement := new(intoto.Statement)
-
-	switch env.PayloadType {
-	case intoto.PayloadType:
-		err = json.Unmarshal(payload, statement)
-		if err != nil {
-			return nil, fmt.Errorf("failed to unmarshal statement: %w", err)
-		}
-		// TODO: implement other types of envelope
-	default:
-		return nil, fmt.Errorf("unsupported payload type: %s", env.PayloadType)
-	}
-
-	value, err := ast.InterfaceToValue(statement)
-	if err != nil {
-		return nil, err
-	}
-
-	return ast.NewTerm(value), nil
-}
-
-func loadYAML(path string, bs []byte) (interface{}, error) {
-	var x interface{}
-	bs, err := yaml.YAMLToJSON(bs)
-	if err != nil {
-		return nil, fmt.Errorf("%v: error converting YAML to JSON: %v", path, err)
-	}
-	err = opa.UnmarshalJSON(bs, &x)
-	if err != nil {
-		return nil, fmt.Errorf("%s: %w", path, err)
-	}
-	return x, nil
-}

pkg/policy/testdata/mock-tuf-allow/doi/data.yaml

@@ -1 +0,0 @@
-config:

pkg/policy/testdata/mock-tuf-allow/doi/policy.rego

@@ -1,5 +0,0 @@
-package docker
-
-import rego.v1
-
-allow := true