fix: tuf oci image parsing (#142)

* fix: tuf oci image parsing

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @docker/supply-chain-security

.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@31c86eb3b33c9b601a1f60f98dcbfd1d70f379b4 # v1.10.3
+        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]
         # 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@v4
+        with:
+          file: ./coverage.out
+          flags: unittests
+          name: codecov-umbrella
+          fail_ci_if_error: true
+          token: ${{ secrets.CODECOV_TOKEN }}

.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

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.

README.md

@@ -1,2 +1,379 @@
-# 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.
+
+Our overall goal with this project is adoption of the ideas into other open-source projects, rather than to create another standalone tool.
+It would be a great outcome if this library was no longer needed because the functionality was built into other tools.
+
+# 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](./pkg/attest/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](./pkg/attest/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/(.*)$"
+    rewrite: docker.io/library/$1
+```
+
+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.

codecov.yml

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

go.mod

@@ -1,82 +1,203 @@
 module github.com/docker/attest
 
-go 1.22.1
+go 1.22.5
 
 require (
-	github.com/google/go-containerregistry v0.19.1
+	github.com/Masterminds/semver/v3 v3.3.0
+	github.com/aws/aws-sdk-go-v2/config v1.27.31
+	github.com/awslabs/amazon-ecr-credential-helper/ecr-login v0.0.0-20231024185945-8841054dbdb8
+	github.com/containerd/platforms v0.2.1
+	github.com/distribution/reference v0.6.0
+	github.com/go-openapi/runtime v0.28.0
+	github.com/go-openapi/strfmt v0.23.0
+	github.com/google/go-containerregistry v0.20.1
+	github.com/hashicorp/go-cleanhttp v0.5.2
+	github.com/in-toto/in-toto-golang v0.9.0
+	github.com/open-policy-agent/opa v0.67.1
+	github.com/opencontainers/image-spec v1.1.0
+	github.com/package-url/packageurl-go v0.1.3
+	github.com/secure-systems-lab/go-securesystemslib v0.8.0
+	github.com/sigstore/cosign/v2 v2.4.0
+	github.com/sigstore/rekor v1.3.6
+	github.com/sigstore/sigstore/pkg/signature/kms/aws v1.8.8
+	github.com/sigstore/sigstore/pkg/signature/kms/gcp v1.8.8
 	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
+	github.com/testcontainers/testcontainers-go/modules/registry v0.33.0
+	github.com/theupdateframework/go-tuf/v2 v2.0.0
+	google.golang.org/api v0.194.0
+	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 (
+	cloud.google.com/go v0.115.1 // indirect
+	cloud.google.com/go/auth v0.9.1 // indirect
+	cloud.google.com/go/auth/oauth2adapt v0.2.4 // indirect
+	cloud.google.com/go/compute/metadata v0.5.0 // indirect
+	cloud.google.com/go/iam v1.1.12 // indirect
+	cloud.google.com/go/kms v1.18.4 // indirect
+	cloud.google.com/go/longrunning v0.5.11 // indirect
 	dario.cat/mergo v1.0.0 // indirect
-	github.com/Azure/go-ansiterm v0.0.0-20210617225240-d185dfc1b5a1 // indirect
-	github.com/Microsoft/go-winio v0.6.1 // indirect
-	github.com/Microsoft/hcsshim v0.11.4 // indirect
-	github.com/cenkalti/backoff/v4 v4.2.1 // indirect
-	github.com/containerd/containerd v1.7.12 // indirect
+	github.com/Azure/go-ansiterm v0.0.0-20230124172434-306776ec8161 // indirect
+	github.com/Microsoft/go-winio v0.6.2 // indirect
+	github.com/OneOfOne/xxhash v1.2.8 // indirect
+	github.com/ProtonMail/go-crypto v1.0.0 // indirect
+	github.com/agnivade/levenshtein v1.1.1 // indirect
+	github.com/asaskevich/govalidator v0.0.0-20230301143203-a9d515a09cc2 // indirect
+	github.com/aws/aws-sdk-go-v2 v1.30.4 // indirect
+	github.com/aws/aws-sdk-go-v2/credentials v1.17.30 // indirect
+	github.com/aws/aws-sdk-go-v2/feature/ec2/imds v1.16.12 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/configsources v1.3.16 // indirect
+	github.com/aws/aws-sdk-go-v2/internal/endpoints/v2 v2.6.16 // 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 v1.11.4 // indirect
+	github.com/aws/aws-sdk-go-v2/service/internal/presigned-url v1.11.18 // indirect
+	github.com/aws/aws-sdk-go-v2/service/kms v1.35.3 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sso v1.22.5 // indirect
+	github.com/aws/aws-sdk-go-v2/service/ssooidc v1.26.5 // indirect
+	github.com/aws/aws-sdk-go-v2/service/sts v1.30.5 // indirect
+	github.com/aws/smithy-go v1.20.4 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/blang/semver v3.5.1+incompatible // indirect
+	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
+	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/cloudflare/circl v1.3.8 // indirect
+	github.com/containerd/containerd v1.7.20 // indirect
 	github.com/containerd/log v0.1.0 // indirect
-	github.com/containerd/stargz-snapshotter/estargz v0.14.3 // indirect
+	github.com/containerd/stargz-snapshotter/estargz v0.15.1 // indirect
 	github.com/cpuguy83/dockercfg v0.3.1 // indirect
-	github.com/davecgh/go-spew v1.1.1 // indirect
-	github.com/distribution/reference v0.5.0 // indirect
-	github.com/docker/cli v24.0.0+incompatible // indirect
-	github.com/docker/distribution v2.8.2+incompatible // indirect
-	github.com/docker/docker v25.0.5+incompatible // indirect
-	github.com/docker/docker-credential-helpers v0.7.0 // indirect
+	github.com/cyberphone/json-canonicalization v0.0.0-20231217050601-ba74d44ecf5f // 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 v27.1.1+incompatible // indirect
+	github.com/docker/distribution v2.8.3+incompatible // indirect
+	github.com/docker/docker v27.1.1+incompatible // indirect
+	github.com/docker/docker-credential-helpers v0.8.1 // indirect
 	github.com/docker/go-connections v0.5.0 // indirect
 	github.com/docker/go-units v0.5.0 // indirect
+	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
-	github.com/go-logr/logr v1.4.1 // indirect
+	github.com/fsnotify/fsnotify v1.7.0 // indirect
+	github.com/go-chi/chi v4.1.2+incompatible // indirect
+	github.com/go-ini/ini v1.67.0 // indirect
+	github.com/go-jose/go-jose/v4 v4.0.2 // 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-ole/go-ole v1.3.0 // 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
+	github.com/go-openapi/jsonreference v0.21.0 // indirect
+	github.com/go-openapi/loads v0.22.0 // indirect
+	github.com/go-openapi/spec v0.21.0 // indirect
+	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 v1.5.3 // 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 v1.2.1 // indirect
+	github.com/google/s2a-go v0.1.8 // indirect
 	github.com/google/uuid v1.6.0 // indirect
-	github.com/klauspost/compress v1.16.5 // indirect
-	github.com/kr/text v0.2.0 // indirect
-	github.com/letsencrypt/boulder v0.0.0-20230907030200-6d76a0f91e1e // indirect
-	github.com/lufia/plan9stats v0.0.0-20211012122336-39d0f177ccd0 // indirect
+	github.com/googleapis/enterprise-certificate-proxy v0.3.2 // indirect
+	github.com/googleapis/gax-go/v2 v2.13.0 // indirect
+	github.com/gorilla/mux v1.8.1 // indirect
+	github.com/hashicorp/go-retryablehttp v0.7.7 // indirect
+	github.com/hashicorp/hcl v1.0.1-vault-5 // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/jedisct1/go-minisign v0.0.0-20230811132847-661be99b8267 // indirect
+	github.com/jellydator/ttlcache/v3 v3.2.0 // indirect
+	github.com/jmespath/go-jmespath v0.4.0 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/klauspost/compress v1.17.8 // indirect
+	github.com/letsencrypt/boulder v0.0.0-20240620165639-de9c06129bec // indirect
+	github.com/lufia/plan9stats v0.0.0-20240513124658-fba389f38bae // 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/docker-image-spec v1.3.1 // 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/opencontainers/image-spec v1.1.0 // indirect
+	github.com/opentracing/opentracing-go v1.2.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.2 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
-	github.com/pmezard/go-difflib v1.0.0 // indirect
-	github.com/power-devops/perfstat v0.0.0-20210106213030-5aafc221ea8c // indirect
-	github.com/secure-systems-lab/go-securesystemslib v0.8.0 // indirect
-	github.com/shirou/gopsutil/v3 v3.23.12 // indirect
+	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
+	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect
+	github.com/prometheus/client_golang v1.19.1 // 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/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/shibumi/go-pathspec v1.3.0 // indirect
+	github.com/shirou/gopsutil/v3 v3.24.4 // 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/sigstore v1.8.8 // indirect
+	github.com/sigstore/timestamp-authority v1.2.2 // indirect
 	github.com/sirupsen/logrus v1.9.3 // 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 v1.8.1 // indirect
+	github.com/spf13/pflag v1.0.5 // 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/testcontainers/testcontainers-go v0.33.0 // 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/vbatts/tar-split v0.11.3 // indirect
-	github.com/yusufpapurcu/wmi v1.2.3 // 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/trace v1.24.0 // indirect
-	golang.org/x/crypto v0.21.0 // indirect
-	golang.org/x/exp v0.0.0-20230510235704-dd950f8aeaea // indirect
-	golang.org/x/mod v0.16.0 // indirect
-	golang.org/x/sync v0.3.0 // indirect
-	golang.org/x/sys v0.18.0 // indirect
-	golang.org/x/term v0.18.0 // indirect
-	golang.org/x/tools v0.13.0 // indirect
-	google.golang.org/genproto/googleapis/rpc v0.0.0-20230711160842-782d3b101e98 // indirect
-	google.golang.org/grpc v1.58.3 // indirect
-	google.golang.org/protobuf v1.33.0 // indirect
-	gopkg.in/go-jose/go-jose.v2 v2.6.3 // indirect
+	github.com/tklauser/go-sysconf v0.3.14 // indirect
+	github.com/tklauser/numcpus v0.8.0 // indirect
+	github.com/transparency-dev/merkle v0.0.2 // indirect
+	github.com/vbatts/tar-split v0.11.5 // 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 v1.2.4 // 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 v0.52.0 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.53.0 // indirect
+	go.opentelemetry.io/otel v1.28.0 // indirect
+	go.opentelemetry.io/otel/metric v1.28.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.28.0 // indirect
+	go.opentelemetry.io/otel/trace v1.28.0 // indirect
+	go.uber.org/multierr v1.11.0 // indirect
+	go.uber.org/zap v1.27.0 // indirect
+	golang.org/x/crypto v0.26.0 // indirect
+	golang.org/x/exp v0.0.0-20240506185415-9bf2ced13842 // indirect
+	golang.org/x/mod v0.19.0 // indirect
+	golang.org/x/net v0.28.0 // indirect
+	golang.org/x/oauth2 v0.22.0 // indirect
+	golang.org/x/sync v0.8.0 // indirect
+	golang.org/x/sys v0.24.0 // indirect
+	golang.org/x/term v0.23.0 // indirect
+	golang.org/x/text v0.17.0 // indirect
+	golang.org/x/time v0.6.0 // indirect
+	google.golang.org/genproto v0.0.0-20240814211410-ddb44dafa142 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20240730163845-b1a4ccb954bf // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20240814211410-ddb44dafa142 // indirect
+	google.golang.org/grpc v1.65.0 // indirect
+	google.golang.org/protobuf v1.34.2 // indirect
+	gopkg.in/ini.v1 v1.67.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/klog/v2 v2.120.1 // 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

@@ -2,12 +2,46 @@ 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/test/test.go

@@ -1,10 +1,26 @@
 package test
 
 import (
+	"context"
 	"os"
+	"path/filepath"
 	"testing"
+
+	"github.com/docker/attest/pkg/signerverifier"
+	"github.com/docker/attest/pkg/tlog"
+	"github.com/secure-systems-lab/go-securesystemslib/dsse"
 )
 
+const (
+	UseMockTL  = true
+	UseMockKMS = true
+
+	AWSRegion    = "us-east-1"
+	AWSKMSKeyARN = "arn:aws:kms:us-east-1:175142243308:alias/doi-signing" // sandbox
+)
+
+var UnsignedTestImage = filepath.Join("..", "..", "test", "testdata", "unsigned-test-image")
+
 func CreateTempDir(t *testing.T, dir, pattern string) string {
 	// Create a temporary directory for output oci layout
 	tempDir, err := os.MkdirTemp(dir, pattern)
@@ -20,3 +36,38 @@ func CreateTempDir(t *testing.T, dir, pattern string) string {
 	})
 	return tempDir
 }
+
+func GetMockSigner(_ context.Context) (dsse.SignerVerifier, error) {
+	priv, err := os.ReadFile(filepath.Join("..", "..", "test", "testdata", "test-signing-key.pem"))
+	if err != nil {
+		return nil, err
+	}
+	return signerverifier.LoadKeyPair(priv)
+}
+
+func Setup(t *testing.T) (context.Context, dsse.SignerVerifier) {
+	var tl tlog.TL
+	if UseMockTL {
+		tl = tlog.GetMockTL()
+	} else {
+		tl = &tlog.RekorTL{}
+	}
+
+	ctx := tlog.WithTL(context.Background(), tl)
+
+	var signer dsse.SignerVerifier
+	var err error
+	if UseMockKMS {
+		signer, err = GetMockSigner(ctx)
+		if err != nil {
+			t.Fatal(err)
+		}
+	} else {
+		signer, err = signerverifier.GetAWSSigner(ctx, AWSKMSKeyARN, AWSRegion)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	return ctx, signer
+}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/1fd0d9781f02486718fcbd7724db0e4c4ba47b649930cec22a3e7e6b6077ba38

@@ -1 +0,0 @@
-{"signatures":[{"keyid":"198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3","sig":"3044022039b56cd2e3597df74e57d200a652ba020cdc9a8cd050bd65b5f8e2640d50691d02205e073e4b6fc260acc64327a331e4440601af5b1cbff594ea91cf7b70d5828fb1"}],"signed":{"_type":"snapshot","expires":"2034-04-03T15:59:47Z","meta":{"targets.json":{"version":5},"test-role.json":{"version":3}},"spec_version":"1.0.31","version":6}}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/4c1054844dba3241525cbd71ff9e58becca652fb1ce4a0e6ea55a01c4ec41950

@@ -1 +0,0 @@
-{"signatures":[{"keyid":"198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3","sig":"3045022011f2afa9b448fcbbac983c11fc3e264e95d5d7a9c9527b09d83a316ee762635f022100d05197a78ccc7a713ebdb0bccb44844f67a7c5208af8d346e201064b7ce11055"}],"signed":{"_type":"timestamp","expires":"2034-04-03T15:59:47Z","meta":{"snapshot.json":{"version":6}},"spec_version":"1.0.31","version":6}}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/a152e59e7b58a3a1ec718192b07fbf630d2fe2d80a6f1a9dc09e1321cbd338a7

@@ -1 +0,0 @@
-{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.oci.image.config.v1+json","size":669,"digest":"sha256:ad4cacc170229608305ffccd8d09eeb59578fcb72ae394763cf7ef492175b1ee"},"layers":[{"mediaType":"application/vnd.tuf.metadata+json","size":2607,"digest":"sha256:a2e026ce65c198ee68a7ed2df6978ed0287bb38342f6ddb7bf934a456f1d6f87","annotations":{"tuf.io/filename":"2.root.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":2200,"digest":"sha256:61a98e1e86ae279e59415d927e38beae430d7e6d2bd6207054179429ea9b6763","annotations":{"tuf.io/filename":"1.root.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":410,"digest":"sha256:1fd0d9781f02486718fcbd7724db0e4c4ba47b649930cec22a3e7e6b6077ba38","annotations":{"tuf.io/filename":"6.snapshot.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":1683,"digest":"sha256:ea7713eb649ca1a33d79ebdccda9f7f066595b1b2c6e37e52dbfd250f5287260","annotations":{"tuf.io/filename":"5.targets.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":383,"digest":"sha256:4c1054844dba3241525cbd71ff9e58becca652fb1ce4a0e6ea55a01c4ec41950","annotations":{"tuf.io/filename":"timestamp.json"}}]}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/a2e026ce65c198ee68a7ed2df6978ed0287bb38342f6ddb7bf934a456f1d6f87

@@ -1 +0,0 @@
-{"signatures":[{"keyid":"b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09","sig":"3066023100e99acc5f74777ebf40376b60f0216e8fe1829c1a49a5f6a6899126c15de1df7a56533baf493b2b53159c50843a289102023100b6a006b24da62ea0b743fbe38e1497ff485bf3a0833894985fc27a0305ad0693eeb968a7b52723ed3c49af8bef2027b6"},{"keyid":"81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664","sig":"30440220136debcc2f60dd1d63c9c2704f9b13c2cb2f5d2df58ea93f07f7c10f54f36742022059d7f8c6620e33506c6f1766394a32f86c9b008328f6398831ba7ebcf4ce0838"}],"signed":{"_type":"root","consistent_snapshot":true,"expires":"2034-04-03T08:45:50Z","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"},"81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664":{"keytype":"ecdsa","keyval":{"public":"-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEWmhpAfB7Q53UNluMhpkDxXXup4E0\n2Hh4PSgHC1Yh6brGl6Akq9a4io55LtZTk5mnCTqxuB+rc5cI/yaNUeWEqQ==\n-----END PUBLIC KEY-----\n"},"scheme":"ecdsa-sha2-nistp256","x-tuf-on-ci-keyowner":"@kipz"},"b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09":{"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"}},"roles":{"root":{"keyids":["b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09","81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664"],"threshold":1},"snapshot":{"keyids":["198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3"],"threshold":1,"x-tuf-on-ci-expiry-period":3650,"x-tuf-on-ci-signing-period":60},"targets":{"keyids":["b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09","81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664"],"threshold":1},"timestamp":{"keyids":["198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3"],"threshold":1,"x-tuf-on-ci-expiry-period":3650,"x-tuf-on-ci-signing-period":60}},"spec_version":"1.0.31","version":2,"x-tuf-on-ci-expiry-period":3650,"x-tuf-on-ci-signing-period":60}}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/a744a2f1e62ae4ce410822b5e3f5508dbaf6a76768a9d23741828172bab1dc97

@@ -1 +0,0 @@
-{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.oci.image.config.v1+json","size":669,"digest":"sha256:c927b30f17fa8c64e3c20b8f92b7e348733f9c1281b5b7e6b6d669a8a74230a7"},"layers":[{"mediaType":"application/vnd.tuf.metadata+json","size":2200,"digest":"sha256:61a98e1e86ae279e59415d927e38beae430d7e6d2bd6207054179429ea9b6763","annotations":{"tuf.io/filename":"1.root.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":2607,"digest":"sha256:a2e026ce65c198ee68a7ed2df6978ed0287bb38342f6ddb7bf934a456f1d6f87","annotations":{"tuf.io/filename":"2.root.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":410,"digest":"sha256:1fd0d9781f02486718fcbd7724db0e4c4ba47b649930cec22a3e7e6b6077ba38","annotations":{"tuf.io/filename":"6.snapshot.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":1683,"digest":"sha256:ea7713eb649ca1a33d79ebdccda9f7f066595b1b2c6e37e52dbfd250f5287260","annotations":{"tuf.io/filename":"5.targets.json"}},{"mediaType":"application/vnd.tuf.metadata+json","size":383,"digest":"sha256:4c1054844dba3241525cbd71ff9e58becca652fb1ce4a0e6ea55a01c4ec41950","annotations":{"tuf.io/filename":"timestamp.json"}}]}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/ad4cacc170229608305ffccd8d09eeb59578fcb72ae394763cf7ef492175b1ee

@@ -1 +0,0 @@
-{"architecture":"","created":"0001-01-01T00:00:00Z","history":[{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"}],"os":"","rootfs":{"type":"layers","diff_ids":["sha256:a2e026ce65c198ee68a7ed2df6978ed0287bb38342f6ddb7bf934a456f1d6f87","sha256:61a98e1e86ae279e59415d927e38beae430d7e6d2bd6207054179429ea9b6763","sha256:1fd0d9781f02486718fcbd7724db0e4c4ba47b649930cec22a3e7e6b6077ba38","sha256:ea7713eb649ca1a33d79ebdccda9f7f066595b1b2c6e37e52dbfd250f5287260","sha256:4c1054844dba3241525cbd71ff9e58becca652fb1ce4a0e6ea55a01c4ec41950"]},"config":{}}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/c927b30f17fa8c64e3c20b8f92b7e348733f9c1281b5b7e6b6d669a8a74230a7

@@ -1 +0,0 @@
-{"architecture":"","created":"0001-01-01T00:00:00Z","history":[{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"},{"created":"0001-01-01T00:00:00Z"}],"os":"","rootfs":{"type":"layers","diff_ids":["sha256:61a98e1e86ae279e59415d927e38beae430d7e6d2bd6207054179429ea9b6763","sha256:a2e026ce65c198ee68a7ed2df6978ed0287bb38342f6ddb7bf934a456f1d6f87","sha256:1fd0d9781f02486718fcbd7724db0e4c4ba47b649930cec22a3e7e6b6077ba38","sha256:ea7713eb649ca1a33d79ebdccda9f7f066595b1b2c6e37e52dbfd250f5287260","sha256:4c1054844dba3241525cbd71ff9e58becca652fb1ce4a0e6ea55a01c4ec41950"]},"config":{}}

internal/test/testdata/test-repo-oci/metadata/blobs/sha256/ea7713eb649ca1a33d79ebdccda9f7f066595b1b2c6e37e52dbfd250f5287260

@@ -1 +0,0 @@
-{"signatures":[{"keyid":"b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09","sig":""},{"keyid":"81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664","sig":"3046022100f892a496c9bd96082e3b06d5eae85429355876b8eb455aa04b53ab9051911d90022100a3e89c29b15bccfc2877278c0fb2d3b34500da6351e245ad0b3f8c0ae6b67eff"}],"signed":{"_type":"targets","delegations":{"keys":{"81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664":{"keytype":"ecdsa","keyval":{"public":"-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEWmhpAfB7Q53UNluMhpkDxXXup4E0\n2Hh4PSgHC1Yh6brGl6Akq9a4io55LtZTk5mnCTqxuB+rc5cI/yaNUeWEqQ==\n-----END PUBLIC KEY-----\n"},"scheme":"ecdsa-sha2-nistp256","x-tuf-on-ci-keyowner":"@kipz"},"b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09":{"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"}},"roles":[{"keyids":["b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09","81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664"],"name":"test-role","paths":["test-role/*","test-role/*/*","test-role/*/*/*","test-role/*/*/*/*"],"terminating":true,"threshold":1}]},"expires":"2034-04-03T15:28:29Z","spec_version":"1.0.31","targets":{"test.txt":{"hashes":{"sha256":"02119a076ec3878c736c3a95e20794f5a8d5bce3d7ecc264681bb7334ca2e24b"},"length":31}},"version":5,"x-tuf-on-ci-expiry-period":3650,"x-tuf-on-ci-signing-period":60}}

internal/test/testdata/test-repo-oci/metadata/test-role/blobs/sha256/2b2d4fba192ec164e05e6d90399c5cf4a45e4fe2ddebb9066c55aa2bcf0a73d3

@@ -1 +0,0 @@
-{"signatures":[{"keyid":"b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09","sig":""},{"keyid":"81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664","sig":"3044022015b6ebe9d30895e3be20e707a6738e38460197d90cae3dc37527ddb7c437868602207f85f3d4e068bef4c51a749f5d166cc7fe2cb9483999ea197e72395081c3aa61"}],"signed":{"_type":"targets","expires":"2034-04-03T15:39:02Z","spec_version":"1.0.31","targets":{"test-role/dir1/dir2/dir3/myfile.txt":{"hashes":{"sha256":"ea230621c53e0bb858ea5526125414f8957fb29c08350528d50a162c620f36b1"},"length":10},"test-role/test.txt":{"hashes":{"sha256":"d1bb6181284970ae43fbbc88b5e72f9a5942ebac20588aa0c4bf78ba621e1ee2"},"length":32}},"version":3,"x-tuf-on-ci-expiry-period":3650,"x-tuf-on-ci-signing-period":60}}

internal/test/testdata/test-repo-oci/metadata/test-role/blobs/sha256/7c8d8f5dfca62068e3a4b18bb41cf85dad23ec9cdc7d7d2e10bc37b86ebffff5

@@ -1 +0,0 @@
-{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.oci.image.config.v1+json","size":233,"digest":"sha256:9edf24c022c2cd6796e87f49ec6a6ea2fad3e7c939c32a8219aaa4726792457c"},"layers":[{"mediaType":"application/vnd.tuf.metadata+json","size":764,"digest":"sha256:2b2d4fba192ec164e05e6d90399c5cf4a45e4fe2ddebb9066c55aa2bcf0a73d3","annotations":{"tuf.io/filename":"3.test-role.json"}}]}

internal/test/testdata/test-repo-oci/targets/test-role/blobs/sha256/8d320e9d3f3663613df6e4fca1651604a6c0323011023145a140b38f02105b04

@@ -1 +0,0 @@
-{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.oci.image.config.v1+json","size":233,"digest":"sha256:0b6b8fdb10421310b9aca2f1fb6ce51537baa243fb9fccca03f2ff3c15fb52f8"},"layers":[{"mediaType":"application/vnd.tuf.target","size":10,"digest":"sha256:ea230621c53e0bb858ea5526125414f8957fb29c08350528d50a162c620f36b1","annotations":{"tuf.io/filename":"ea230621c53e0bb858ea5526125414f8957fb29c08350528d50a162c620f36b1.myfile.txt"}}]}

internal/test/testdata/test-repo-oci/targets/test-role/blobs/sha256/ea230621c53e0bb858ea5526125414f8957fb29c08350528d50a162c620f36b1

@@ -1 +0,0 @@
-hello tuf

internal/test/testdata/test-repo-oci/targets/test-role/index.json

@@ -1 +0,0 @@
-{"schemaVersion":2,"mediaType":"application/vnd.oci.image.index.v1+json","manifests":[{"mediaType":"application/vnd.oci.image.manifest.v1+json","size":495,"digest":"sha256:8d320e9d3f3663613df6e4fca1651604a6c0323011023145a140b38f02105b04","annotations":{"tuf.io/filename":"test-role/dir1/dir2/dir3/ea230621c53e0bb858ea5526125414f8957fb29c08350528d50a162c620f36b1.myfile.txt"}},{"mediaType":"application/vnd.oci.image.manifest.v1+json","size":493,"digest":"sha256:0a4afcdad291941327b070ab4feaf052425fbf4ded864bc55c18cfefec8be6e2","annotations":{"tuf.io/filename":"test-role/d1bb6181284970ae43fbbc88b5e72f9a5942ebac20588aa0c4bf78ba621e1ee2.test.txt"}}]}

internal/test/testdata/test-repo/metadata/3.test-role.json

@@ -1,34 +0,0 @@
-{
- "signatures": [
-  {
-   "keyid": "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09",
-   "sig": ""
-  },
-  {
-   "keyid": "81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664",
-   "sig": "3044022015b6ebe9d30895e3be20e707a6738e38460197d90cae3dc37527ddb7c437868602207f85f3d4e068bef4c51a749f5d166cc7fe2cb9483999ea197e72395081c3aa61"
-  }
- ],
- "signed": {
-  "_type": "targets",
-  "expires": "2034-04-03T15:39:02Z",
-  "spec_version": "1.0.31",
-  "targets": {
-   "test-role/dir1/dir2/dir3/myfile.txt": {
-    "hashes": {
-     "sha256": "ea230621c53e0bb858ea5526125414f8957fb29c08350528d50a162c620f36b1"
-    },
-    "length": 10
-   },
-   "test-role/test.txt": {
-    "hashes": {
-     "sha256": "d1bb6181284970ae43fbbc88b5e72f9a5942ebac20588aa0c4bf78ba621e1ee2"
-    },
-    "length": 32
-   }
-  },
-  "version": 3,
-  "x-tuf-on-ci-expiry-period": 3650,
-  "x-tuf-on-ci-signing-period": 60
- }
-}

internal/test/testdata/test-repo/metadata/5.targets.json

@@ -1,65 +0,0 @@
-{
- "signatures": [
-  {
-   "keyid": "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09",
-   "sig": ""
-  },
-  {
-   "keyid": "81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664",
-   "sig": "3046022100f892a496c9bd96082e3b06d5eae85429355876b8eb455aa04b53ab9051911d90022100a3e89c29b15bccfc2877278c0fb2d3b34500da6351e245ad0b3f8c0ae6b67eff"
-  }
- ],
- "signed": {
-  "_type": "targets",
-  "delegations": {
-   "keys": {
-    "81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664": {
-     "keytype": "ecdsa",
-     "keyval": {
-      "public": "-----BEGIN PUBLIC KEY-----\nMFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEWmhpAfB7Q53UNluMhpkDxXXup4E0\n2Hh4PSgHC1Yh6brGl6Akq9a4io55LtZTk5mnCTqxuB+rc5cI/yaNUeWEqQ==\n-----END PUBLIC KEY-----\n"
-     },
-     "scheme": "ecdsa-sha2-nistp256",
-     "x-tuf-on-ci-keyowner": "@kipz"
-    },
-    "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09": {
-     "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"
-    }
-   },
-   "roles": [
-    {
-     "keyids": [
-      "b7474a42f2588fa92ed4a2ebea6047a7b1b2f7351f1cfe0912732c0d0fb0fc09",
-      "81cf5a78d6ea2cd904256b9d814b340289b765e6f75ec4397e4ebb7586cab664"
-     ],
-     "name": "test-role",
-     "paths": [
-      "test-role/*",
-      "test-role/*/*",
-      "test-role/*/*/*",
-      "test-role/*/*/*/*"
-     ],
-     "terminating": true,
-     "threshold": 1
-    }
-   ]
-  },
-  "expires": "2034-04-03T15:28:29Z",
-  "spec_version": "1.0.31",
-  "targets": {
-   "test.txt": {
-    "hashes": {
-     "sha256": "02119a076ec3878c736c3a95e20794f5a8d5bce3d7ecc264681bb7334ca2e24b"
-    },
-    "length": 31
-   }
-  },
-  "version": 5,
-  "x-tuf-on-ci-expiry-period": 3650,
-  "x-tuf-on-ci-signing-period": 60
- }
-}

internal/test/testdata/test-repo/metadata/6.snapshot.json

@@ -1,22 +0,0 @@
-{
- "signatures": [
-  {
-   "keyid": "198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3",
-   "sig": "3044022039b56cd2e3597df74e57d200a652ba020cdc9a8cd050bd65b5f8e2640d50691d02205e073e4b6fc260acc64327a331e4440601af5b1cbff594ea91cf7b70d5828fb1"
-  }
- ],
- "signed": {
-  "_type": "snapshot",
-  "expires": "2034-04-03T15:59:47Z",
-  "meta": {
-   "targets.json": {
-    "version": 5
-   },
-   "test-role.json": {
-    "version": 3
-   }
-  },
-  "spec_version": "1.0.31",
-  "version": 6
- }
-}

internal/test/testdata/test-repo/metadata/timestamp.json

@@ -1,19 +0,0 @@
-{
- "signatures": [
-  {
-   "keyid": "198f00ff96ea7cbfa7eac480cc9bfc43ce13bb434b901011ab777856533997d3",
-   "sig": "3045022011f2afa9b448fcbbac983c11fc3e264e95d5d7a9c9527b09d83a316ee762635f022100d05197a78ccc7a713ebdb0bccb44844f67a7c5208af8d346e201064b7ce11055"
-  }
- ],
- "signed": {
-  "_type": "timestamp",
-  "expires": "2034-04-03T15:59:47Z",
-  "meta": {
-   "snapshot.json": {
-    "version": 6
-   }
-  },
-  "spec_version": "1.0.31",
-  "version": 6
- }
-}

internal/test/testdata/test-repo/targets/test-role/dir1/dir2/dir3/ea230621c53e0bb858ea5526125414f8957fb29c08350528d50a162c620f36b1.myfile.txt

@@ -1 +0,0 @@
-hello tuf

internal/util/crypto.go

@@ -5,9 +5,11 @@ 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 SHA256(data []byte) []byte {
+	h := sha256.Sum256(data)
+	return h[:]
 }

pkg/attest/README.md

@@ -0,0 +1,2 @@
+## attest
+This package implements the top-level signing and verification methods.

pkg/attest/example_sign_test.go

@@ -0,0 +1,76 @@
+package attest_test
+
+import (
+	"context"
+
+	"github.com/docker/attest/pkg/attest"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/signerverifier"
+	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
+	opts := &attestation.SigningOptions{
+		SkipTL: true, // skip trust logging to a transparency log
+	}
+
+	// load image index with unsigned attestation-manifests
+	ref := "docker/image-signer-verifier:latest"
+	attIdx, err := oci.IndexFromRemote(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(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)
+	}
+}

pkg/attest/example_verify_test.go

@@ -0,0 +1,54 @@
+package attest_test
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/docker/attest/pkg/attest"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/policy"
+	"github.com/docker/attest/pkg/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")
+	}
+}

pkg/attest/sign.go

@@ -0,0 +1,29 @@
+package attest
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/docker/attest/pkg/attestation"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/secure-systems-lab/go-securesystemslib/dsse"
+)
+
+// this is only relevant if there are (unsigned) in-toto statements.
+func SignStatements(ctx context.Context, idx v1.ImageIndex, signer dsse.SignerVerifier, opts *attestation.SigningOptions) ([]*attestation.Manifest, error) {
+	// extract attestation manifests from index
+	attestationManifests, err := attestation.ManifestsFromIndex(idx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load attestation manifests from index: %w", err)
+	}
+	// sign every attestation layer in each manifest
+	for _, manifest := range attestationManifests {
+		for _, layer := range manifest.OriginalLayers {
+			err = manifest.Add(ctx, signer, layer.Statement, opts)
+			if err != nil {
+				return nil, fmt.Errorf("failed to sign attestation layer %w", err)
+			}
+		}
+	}
+	return attestationManifests, nil
+}

pkg/attest/sign_test.go

@@ -0,0 +1,85 @@
+package attest
+
+import (
+	"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"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	v02 "github.com/in-toto/in-toto-golang/in_toto/slsa_provenance/v0.2"
+	"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")
+	PassMirrorPolicyDir = filepath.Join("..", "..", "test", "testdata", "local-policy-mirror")
+	PassNoTLPolicyDir   = filepath.Join("..", "..", "test", "testdata", "local-policy-no-tl")
+	FailPolicyDir       = filepath.Join("..", "..", "test", "testdata", "local-policy-fail")
+	InputsPolicyDir     = filepath.Join("..", "..", "test", "testdata", "local-policy-inputs")
+	EmptyPolicyDir      = filepath.Join("..", "..", "test", "testdata", "local-policy-no-policies")
+	TestTempDir         = "attest-sign-test"
+)
+
+func TestSignVerifyOCILayout(t *testing.T) {
+	ctx, signer := test.Setup(t)
+
+	testCases := []struct {
+		name                 string
+		TestImage            string
+		expectedStatements   int
+		expectedAttestations int
+		replace              bool
+	}{
+		{"signed replaced", test.UnsignedTestImage, 0, 4, true},
+		{"without replace", test.UnsignedTestImage, 4, 4, false},
+		// image without provenance doesn't fail
+		{"no provenance (replace)", NoProvenanceImage, 0, 2, true},
+		{"no provenance (no replace)", NoProvenanceImage, 2, 2, false},
+	}
+	policyOpts := &policy.Options{
+		LocalPolicyDir: PassPolicyDir,
+		DisableTUF:     true,
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			outputLayout := test.CreateTempDir(t, "", TestTempDir)
+			opts := &attestation.SigningOptions{}
+			attIdx, err := oci.IndexFromPath(tc.TestImage)
+			require.NoError(t, err)
+			signedManifests, err := SignStatements(ctx, attIdx.Index, signer, opts)
+			require.NoError(t, err)
+			signedIndex := attIdx.Index
+			signedIndex, err = attestation.UpdateIndexImages(signedIndex, signedManifests, attestation.WithReplacedLayers(tc.replace))
+			require.NoError(t, err)
+			spec, err := oci.ParseImageSpec(oci.LocalPrefix + outputLayout)
+			require.NoError(t, err)
+			err = oci.SaveIndex([]*oci.ImageSpec{spec}, signedIndex, attIdx.Name)
+			require.NoError(t, err)
+			policy, err := Verify(ctx, spec, policyOpts)
+			require.NoError(t, err)
+			assert.Equalf(t, OutcomeSuccess, policy.Outcome, "Policy should have been found")
+
+			var allEnvelopes []*attestation.AnnotatedStatement
+			for _, predicate := range []string{intoto.PredicateSPDX, v02.PredicateSLSAProvenance, attestation.VSAPredicateType} {
+				mt, _ := attestation.DSSEMediaType(predicate)
+				statements, err := attestation.ExtractAnnotatedStatements(outputLayout, mt)
+				require.NoError(t, err)
+				allEnvelopes = append(allEnvelopes, statements...)
+
+				for _, stmt := range statements {
+					assert.Equalf(t, predicate, stmt.Annotations[attestation.InTotoPredicateType], "expected predicate-type annotation to be set to %s, got %s", predicate, stmt.Annotations[attestation.InTotoPredicateType])
+					assert.Equalf(t, attestation.LifecycleStageExperimental, stmt.Annotations[attestation.InTotoReferenceLifecycleStage], "expected reference lifecycle stage annotation to be set to %s, got %s", attestation.LifecycleStageExperimental, stmt.Annotations[attestation.InTotoReferenceLifecycleStage])
+				}
+			}
+			assert.Equalf(t, tc.expectedAttestations, len(allEnvelopes), "expected %d attestations, got %d", tc.expectedAttestations, len(allEnvelopes))
+			statements, err := attestation.ExtractAnnotatedStatements(outputLayout, intoto.PayloadType)
+			require.NoError(t, err)
+			assert.Equalf(t, tc.expectedStatements, len(statements), "expected %d statement, got %d", tc.expectedStatements, len(statements))
+		})
+	}
+}

pkg/attest/types.go

@@ -0,0 +1,37 @@
+package attest
+
+import (
+	"fmt"
+
+	"github.com/docker/attest/pkg/policy"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+)
+
+type Outcome string
+
+const (
+	OutcomeSuccess  Outcome = "success"
+	OutcomeFailure  Outcome = "failure"
+	OutcomeNoPolicy Outcome = "no_policy"
+)
+
+func (o Outcome) StringForVSA() (string, error) {
+	switch o {
+	case OutcomeSuccess:
+		return "PASSED", nil
+	case OutcomeFailure:
+		return "FAILED", nil
+	default:
+		return "", fmt.Errorf("unknown outcome: %s", o)
+	}
+}
+
+type VerificationResult struct {
+	Outcome           Outcome
+	Policy            *policy.Policy
+	Input             *policy.Input
+	VSA               *intoto.Statement
+	Violations        []policy.Violation
+	SubjectDescriptor *v1.Descriptor
+}

pkg/attest/verify.go

@@ -0,0 +1,253 @@
+package attest
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/distribution/reference"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/config"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/policy"
+	"github.com/docker/attest/pkg/tuf"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+)
+
+type Verifier interface {
+	Verify(ctx context.Context, src *oci.ImageSpec) (result *VerificationResult, err error)
+}
+
+type tufVerifier struct {
+	opts      *policy.Options
+	tufClient tuf.Downloader
+}
+
+func NewVerifier(opts *policy.Options) (Verifier, error) {
+	err := populateDefaultOptions(opts)
+	if err != nil {
+		return nil, err
+	}
+	var tufClient tuf.Downloader
+	if !opts.DisableTUF {
+		tufClient, err = tuf.NewClient(opts.TUFClientOptions)
+		if err != nil {
+			return nil, fmt.Errorf("failed to create TUF client: %w", err)
+		}
+	}
+	return &tufVerifier{
+		opts:      opts,
+		tufClient: tufClient,
+	}, nil
+}
+
+func (verifier *tufVerifier) Verify(ctx context.Context, src *oci.ImageSpec) (result *VerificationResult, err error) {
+	// so that we can resolve mapping from the image name earlier
+	detailsResolver, err := policy.CreateImageDetailsResolver(src)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create image details resolver: %w", err)
+	}
+	imageName, err := detailsResolver.ImageName(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve image name: %w", err)
+	}
+	policyResolver := policy.NewResolver(verifier.tufClient, verifier.opts)
+	resolvedPolicy, err := policyResolver.ResolvePolicy(ctx, imageName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve policy: %w", err)
+	}
+
+	if resolvedPolicy == nil {
+		return &VerificationResult{
+			Outcome: OutcomeNoPolicy,
+		}, nil
+	}
+	// this is overriding the mapping with a referrers config. Useful for testing if nothing else
+	if verifier.opts.ReferrersRepo != "" {
+		resolvedPolicy.Mapping.Attestations = &config.AttestationConfig{
+			Repo:  verifier.opts.ReferrersRepo,
+			Style: config.AttestationStyleReferrers,
+		}
+	} else if verifier.opts.AttestationStyle == config.AttestationStyleAttached {
+		resolvedPolicy.Mapping.Attestations = &config.AttestationConfig{
+			Repo:  verifier.opts.ReferrersRepo,
+			Style: config.AttestationStyleAttached,
+		}
+	}
+	// because we have a mapping now, we can select a resolver based on its contents (ie. referrers or attached)
+	resolver, err := policy.CreateAttestationResolver(detailsResolver, resolvedPolicy.Mapping)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create attestation resolver: %w", err)
+	}
+	evaluator := policy.NewRegoEvaluator(verifier.opts.Debug)
+	result, err = VerifyAttestations(ctx, resolver, evaluator, resolvedPolicy)
+	if err != nil {
+		return nil, fmt.Errorf("failed to evaluate policy: %w", err)
+	}
+	return result, nil
+}
+
+func Verify(ctx context.Context, src *oci.ImageSpec, opts *policy.Options) (result *VerificationResult, err error) {
+	verifier, err := NewVerifier(opts)
+	if err != nil {
+		return nil, err
+	}
+	return verifier.Verify(ctx, src)
+}
+
+func populateDefaultOptions(opts *policy.Options) (err error) {
+	if opts.LocalPolicyDir == "" && opts.DisableTUF {
+		return fmt.Errorf("local policy dir must be set if not using TUF")
+	}
+	if opts.LocalTargetsDir == "" {
+		opts.LocalTargetsDir, err = defaultLocalTargetsDir()
+		if err != nil {
+			return err
+		}
+	}
+	if opts.DisableTUF && opts.TUFClientOptions != nil {
+		return fmt.Errorf("TUF client options set but TUF disabled")
+	} else if opts.TUFClientOptions == nil && !opts.DisableTUF {
+		opts.TUFClientOptions = tuf.NewDockerDefaultClientOptions(opts.LocalTargetsDir)
+	}
+
+	if opts.AttestationStyle == "" {
+		opts.AttestationStyle = config.AttestationStyleReferrers
+	}
+	if opts.ReferrersRepo != "" && opts.AttestationStyle != config.AttestationStyleReferrers {
+		return fmt.Errorf("referrers repo specified but attestation source not set to referrers")
+	}
+	return nil
+}
+
+func defaultLocalTargetsDir() (string, error) {
+	homeDir, err := os.UserHomeDir()
+	if err != nil {
+		return "", fmt.Errorf("failed to get user home directory: %w", err)
+	}
+	return filepath.Join(homeDir, ".docker", "tuf"), nil
+}
+
+func toVerificationResult(p *policy.Policy, input *policy.Input, result *policy.Result) (*VerificationResult, error) {
+	dgst, err := oci.SplitDigest(input.Digest)
+	if err != nil {
+		return nil, fmt.Errorf("failed to split digest: %w", err)
+	}
+	subject := intoto.Subject{
+		Name:   input.PURL,
+		Digest: dgst,
+	}
+	resourceURI, err := attestation.ToVSAResourceURI(subject)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create resource uri: %w", err)
+	}
+
+	var outcome Outcome
+	if result.Success {
+		outcome = OutcomeSuccess
+	} else {
+		outcome = OutcomeFailure
+	}
+
+	outcomeStr, err := outcome.StringForVSA()
+	if err != nil {
+		return nil, err
+	}
+
+	vsaPolicy := attestation.VSAPolicy{URI: result.Summary.PolicyURI, DownloadLocation: p.URI, Digest: p.Digest}
+
+	return &VerificationResult{
+		Policy:     p,
+		Outcome:    outcome,
+		Violations: result.Violations,
+		Input:      input,
+		VSA: &intoto.Statement{
+			StatementHeader: intoto.StatementHeader{
+				PredicateType: attestation.VSAPredicateType,
+				Type:          intoto.StatementInTotoV01,
+				Subject:       result.Summary.Subjects,
+			},
+			Predicate: attestation.VSAPredicate{
+				Verifier: attestation.VSAVerifier{
+					ID: result.Summary.Verifier,
+				},
+				TimeVerified:       time.Now().UTC().Format(time.RFC3339),
+				ResourceURI:        resourceURI,
+				Policy:             vsaPolicy,
+				VerificationResult: outcomeStr,
+				VerifiedLevels:     result.Summary.SLSALevels,
+			},
+		},
+	}, nil
+}
+
+func VerifyAttestations(ctx context.Context, resolver attestation.Resolver, evaluator policy.Evaluator, resolvedPolicy *policy.Policy) (*VerificationResult, error) {
+	desc, err := resolver.ImageDescriptor(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get image descriptor: %w", err)
+	}
+	digest := desc.Digest.String()
+	name, err := resolver.ImageName(ctx)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get image name: %w", err)
+	}
+	platform, err := resolver.ImagePlatform(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	if resolvedPolicy.ResolvedName != "" {
+		// this means the name we have is not the one we want to use for policy evaluation
+		// so we need to replace it with the one we resolved during policy resolution.
+		// this can happen if the name is an alias for another image, e.g. if it is a mirror
+		ref, err := reference.ParseNormalizedNamed(name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse image name: %w", err)
+		}
+		oldName := ref.Name()
+		name = strings.Replace(name, oldName, resolvedPolicy.ResolvedName, 1)
+	}
+
+	ref, err := reference.ParseNormalizedNamed(name)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse ref %q: %w", ref, err)
+	}
+	purl, canonical, err := oci.RefToPURL(ref, platform)
+	if err != nil {
+		return nil, fmt.Errorf("failed to convert ref to purl: %w", err)
+	}
+	var tag string
+	if !canonical {
+		// unlike the function name indicates, this adds latest if no tag is present
+		ref = reference.TagNameOnly(ref)
+	}
+
+	if tagged, ok := ref.(reference.Tagged); ok {
+		tag = tagged.Tag()
+	}
+	input := &policy.Input{
+		Digest:         digest,
+		PURL:           purl,
+		Platform:       platform.String(),
+		Domain:         reference.Domain(ref),
+		NormalizedName: reference.Path(ref),
+		FamiliarName:   reference.FamiliarName(ref),
+	}
+	// rego has null strings
+	if tag != "" {
+		input.Tag = tag
+	}
+	result, err := evaluator.Evaluate(ctx, resolver, resolvedPolicy, input)
+	if err != nil {
+		return nil, fmt.Errorf("policy evaluation failed: %w", err)
+	}
+	verificationResult, err := toVerificationResult(resolvedPolicy, input, result)
+	if err != nil {
+		return nil, fmt.Errorf("failed to convert to policy result: %w", err)
+	}
+	verificationResult.SubjectDescriptor = desc
+	return verificationResult, nil
+}

pkg/attest/verify_test.go

@@ -0,0 +1,309 @@
+package attest
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/distribution/reference"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/config"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/policy"
+	"github.com/docker/attest/pkg/tuf"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+var ExampleAttestation = filepath.Join("..", "..", "test", "testdata", "example_attestation.json")
+
+const (
+	LinuxAMD64 = "linux/amd64"
+)
+
+func TestVerifyAttestations(t *testing.T) {
+	ex, err := os.ReadFile(ExampleAttestation)
+	assert.NoError(t, err)
+
+	env := new(attestation.Envelope)
+	err = json.Unmarshal(ex, env)
+	assert.NoError(t, err)
+	resolver := &attestation.MockResolver{
+		Envs: []*attestation.Envelope{env},
+	}
+
+	testCases := []struct {
+		name                  string
+		policyEvaluationError error
+		expectedError         error
+	}{
+		{"policy ok", nil, nil},
+		{"policy error", fmt.Errorf("policy error"), fmt.Errorf("policy evaluation failed: policy error")},
+	}
+	ctx := context.Background()
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			mockPE := policy.MockPolicyEvaluator{
+				EvaluateFunc: func(_ context.Context, _ attestation.Resolver, _ *policy.Policy, _ *policy.Input) (*policy.Result, error) {
+					return policy.AllowedResult(), tc.policyEvaluationError
+				},
+			}
+
+			_, err := VerifyAttestations(ctx, resolver, &mockPE, &policy.Policy{ResolvedName: ""})
+			if tc.expectedError != nil {
+				if assert.Error(t, err) {
+					assert.Equal(t, tc.expectedError.Error(), err.Error())
+				}
+			} else {
+				assert.NoError(t, err)
+			}
+		})
+	}
+}
+
+func TestVSA(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	// setup an image with signed attestations
+	outputLayout := test.CreateTempDir(t, "", TestTempDir)
+
+	opts := &attestation.SigningOptions{}
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+	assert.NoError(t, err)
+	signedManifests, err := SignStatements(ctx, attIdx.Index, signer, opts)
+	require.NoError(t, err)
+	signedIndex := attIdx.Index
+	signedIndex, err = attestation.UpdateIndexImages(signedIndex, signedManifests)
+	require.NoError(t, err)
+
+	// output signed attestations
+	spec, err := oci.ParseImageSpec(oci.LocalPrefix+outputLayout, oci.WithPlatform(LinuxAMD64))
+	require.NoError(t, err)
+	err = oci.SaveIndex([]*oci.ImageSpec{spec}, signedIndex, attIdx.Name)
+	assert.NoError(t, err)
+
+	// mocked vsa query should pass
+	policyOpts := &policy.Options{
+		LocalPolicyDir:   PassPolicyDir,
+		AttestationStyle: config.AttestationStyleAttached,
+		DisableTUF:       true,
+	}
+	results, err := Verify(ctx, spec, policyOpts)
+	require.NoError(t, err)
+	assert.Equal(t, OutcomeSuccess, results.Outcome)
+	assert.Empty(t, results.Violations)
+
+	if assert.NotNil(t, results.Input) {
+		assert.Equal(t, "sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620", results.Input.Digest)
+		assert.NotNil(t, results.Input.Tag)
+	}
+
+	assert.Equal(t, intoto.StatementInTotoV01, results.VSA.Type)
+	assert.Equal(t, attestation.VSAPredicateType, results.VSA.PredicateType)
+	assert.Len(t, results.VSA.Subject, 1)
+
+	require.IsType(t, attestation.VSAPredicate{}, results.VSA.Predicate)
+	attestationPredicate, ok := results.VSA.Predicate.(attestation.VSAPredicate)
+	require.True(t, ok)
+
+	assert.Equal(t, "PASSED", attestationPredicate.VerificationResult)
+	assert.Equal(t, "docker-official-images", attestationPredicate.Verifier.ID)
+	assert.Equal(t, []string{"SLSA_BUILD_LEVEL_3"}, attestationPredicate.VerifiedLevels)
+	assert.Equal(t, PassPolicyDir+"/policy.rego", attestationPredicate.Policy.DownloadLocation)
+	assert.Equal(t, "https://docker.com/official/policy/v0.1", attestationPredicate.Policy.URI)
+	assert.Equal(t, map[string]string{"sha256": "d71d6b8f49fcba1295b16f5394dd5863a14e4277eb663d66d8c48e392509afe0"}, attestationPredicate.Policy.Digest)
+}
+
+func TestVerificationFailure(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	// setup an image with signed attestations
+	outputLayout := test.CreateTempDir(t, "", TestTempDir)
+
+	opts := &attestation.SigningOptions{}
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+	assert.NoError(t, err)
+	signedManifests, err := SignStatements(ctx, attIdx.Index, signer, opts)
+	require.NoError(t, err)
+	signedIndex := attIdx.Index
+	signedIndex, err = attestation.UpdateIndexImages(signedIndex, signedManifests, attestation.WithReplacedLayers(true))
+	require.NoError(t, err)
+
+	// output signed attestations
+	spec, err := oci.ParseImageSpec(oci.LocalPrefix+outputLayout, oci.WithPlatform(LinuxAMD64))
+	require.NoError(t, err)
+	err = oci.SaveIndex([]*oci.ImageSpec{spec}, signedIndex, attIdx.Name)
+	assert.NoError(t, err)
+
+	// mocked vsa query should fail
+	policyOpts := &policy.Options{
+		LocalPolicyDir:   FailPolicyDir,
+		AttestationStyle: config.AttestationStyleAttached,
+		DisableTUF:       true,
+	}
+	results, err := Verify(ctx, spec, policyOpts)
+	require.NoError(t, err)
+	assert.Equal(t, OutcomeFailure, results.Outcome)
+	assert.Len(t, results.Violations, 1)
+
+	violation := results.Violations[0]
+	assert.Equal(t, "missing_attestation", violation.Type)
+	assert.Equal(t, "Attestation missing for subject", violation.Description)
+	assert.Nil(t, violation.Attestation)
+
+	assert.Equal(t, intoto.StatementInTotoV01, results.VSA.Type)
+	assert.Equal(t, attestation.VSAPredicateType, results.VSA.PredicateType)
+	assert.Len(t, results.VSA.Subject, 1)
+
+	require.IsType(t, attestation.VSAPredicate{}, results.VSA.Predicate)
+	attestationPredicate, ok := results.VSA.Predicate.(attestation.VSAPredicate)
+	require.True(t, ok)
+
+	assert.Equal(t, "FAILED", attestationPredicate.VerificationResult)
+	assert.Equal(t, "docker-official-images", attestationPredicate.Verifier.ID)
+	assert.Equal(t, []string{"SLSA_BUILD_LEVEL_3"}, attestationPredicate.VerifiedLevels)
+	assert.Equal(t, FailPolicyDir+"/policy.rego", attestationPredicate.Policy.DownloadLocation)
+	assert.Equal(t, "https://docker.com/official/policy/v0.1", attestationPredicate.Policy.URI)
+	assert.Equal(t, map[string]string{"sha256": "ad045e1bd7cd602d90196acf68f2c57d7b51565d59e6e30e30d94ae86aa16201"}, attestationPredicate.Policy.Digest)
+}
+
+func TestSignVerify(t *testing.T) {
+	ctx, signer := test.Setup(t)
+	// setup an image with signed attestations
+	outputLayout := test.CreateTempDir(t, "", TestTempDir)
+
+	testCases := []struct {
+		name               string
+		signTL             bool
+		policyDir          string
+		imageName          string
+		expectedNonSuccess Outcome
+	}{
+		{name: "happy path", signTL: true, policyDir: PassNoTLPolicyDir},
+		{name: "sign tl, verify no tl", signTL: true, policyDir: PassPolicyDir},
+		{name: "no tl", signTL: false, policyDir: PassPolicyDir},
+		{name: "mirror", signTL: true, policyDir: PassMirrorPolicyDir, imageName: "mirror.org/library/test-image:test"},
+		{name: "mirror no match", signTL: true, policyDir: PassMirrorPolicyDir, imageName: "incorrect.org/library/test-image:test", expectedNonSuccess: OutcomeNoPolicy},
+		{name: "verify inputs", signTL: false, policyDir: InputsPolicyDir},
+	}
+
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+	assert.NoError(t, err)
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			opts := &attestation.SigningOptions{
+				SkipTL: tc.signTL,
+			}
+
+			signedManifests, err := SignStatements(ctx, attIdx.Index, signer, opts)
+			require.NoError(t, err)
+			signedIndex := attIdx.Index
+			signedIndex, err = attestation.UpdateIndexImages(signedIndex, signedManifests, attestation.WithReplacedLayers(true))
+			require.NoError(t, err)
+
+			imageName := tc.imageName
+			if imageName == "" {
+				imageName = attIdx.Name
+			}
+			// output signed attestations
+			spec, err := oci.ParseImageSpec(oci.LocalPrefix+outputLayout, oci.WithPlatform(LinuxAMD64))
+			require.NoError(t, err)
+			err = oci.SaveIndex([]*oci.ImageSpec{spec}, signedIndex, imageName)
+			require.NoError(t, err)
+
+			policyOpts := &policy.Options{
+				LocalPolicyDir: tc.policyDir,
+				DisableTUF:     true,
+			}
+			results, err := Verify(ctx, spec, policyOpts)
+			require.NoError(t, err)
+			if tc.expectedNonSuccess != "" {
+				assert.Equal(t, tc.expectedNonSuccess, results.Outcome)
+				return
+			}
+			assert.Equal(t, OutcomeSuccess, results.Outcome)
+			platform, err := oci.ParsePlatform(LinuxAMD64)
+			require.NoError(t, err)
+
+			ref, err := reference.ParseNormalizedNamed(attIdx.Name)
+			require.NoError(t, err)
+			expectedPURL, _, err := oci.RefToPURL(ref, platform)
+			require.NoError(t, err)
+			assert.Equal(t, expectedPURL, results.Input.PURL)
+		})
+	}
+}
+
+func TestDefaultOptions(t *testing.T) {
+	testCases := []struct {
+		name             string
+		tufOpts          *tuf.ClientOptions
+		localTargetsDir  string
+		attestationStyle config.AttestationStyle
+		referrersRepo    string
+		expectedError    string
+		disableTuf       bool
+		localPolicyDir   string
+	}{
+		{name: "empty"},
+		{name: "tufClient provided", tufOpts: &tuf.ClientOptions{MetadataSource: "a", TargetsSource: "b"}},
+		{name: "localTargetsDir provided", localTargetsDir: test.CreateTempDir(t, "", TestTempDir)},
+		{name: "attestationStyle provided", attestationStyle: config.AttestationStyleAttached},
+		{name: "referrersRepo provided", referrersRepo: "referrers"},
+		{name: "referrersRepo provided with attached", referrersRepo: "referrers", attestationStyle: config.AttestationStyleAttached, expectedError: "referrers repo specified but attestation source not set to referrers"},
+		{name: "tuf disabled and no local-policy-dir", disableTuf: true, expectedError: "local policy dir must be set if not using TUF"},
+		{name: "tuf disabled but options set", disableTuf: true, tufOpts: &tuf.ClientOptions{MetadataSource: "a", TargetsSource: "b"}, localPolicyDir: "foo", expectedError: "TUF client options set but TUF disabled"},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			defaultTargets, err := defaultLocalTargetsDir()
+			require.NoError(t, err)
+
+			opts := &policy.Options{
+				TUFClientOptions: tc.tufOpts,
+				LocalTargetsDir:  tc.localTargetsDir,
+				AttestationStyle: tc.attestationStyle,
+				ReferrersRepo:    tc.referrersRepo,
+				DisableTUF:       tc.disableTuf,
+				LocalPolicyDir:   tc.localPolicyDir,
+			}
+
+			err = populateDefaultOptions(opts)
+			if tc.expectedError != "" {
+				require.Error(t, err)
+				assert.Equal(t, tc.expectedError, err.Error())
+				return
+			}
+
+			require.NoError(t, err)
+
+			if tc.localTargetsDir != "" {
+				assert.Equal(t, tc.localTargetsDir, opts.LocalTargetsDir)
+			} else {
+				assert.Equal(t, defaultTargets, opts.LocalTargetsDir)
+			}
+
+			if tc.attestationStyle != "" {
+				assert.Equal(t, tc.attestationStyle, opts.AttestationStyle)
+			} else {
+				assert.Equal(t, config.AttestationStyleReferrers, opts.AttestationStyle)
+			}
+
+			if tc.tufOpts != nil {
+				assert.Equal(t, tc.tufOpts, opts.TUFClientOptions)
+			} else {
+				assert.NotNil(t, opts.TUFClientOptions)
+			}
+
+			if tc.referrersRepo != "" {
+				assert.Equal(t, tc.referrersRepo, opts.ReferrersRepo)
+			} else {
+				assert.Empty(t, opts.ReferrersRepo)
+			}
+		})
+	}
+}

pkg/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.

pkg/attestation/attestation.go

@@ -0,0 +1,444 @@
+package attestation
+
+import (
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"maps"
+	"strings"
+
+	"github.com/docker/attest/pkg/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
+		stmt := new(intoto.Statement)
+		if mt == types.MediaType(intoto.PayloadType) {
+			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) ([]*Envelope, error) {
+	var envs []*Envelope
+	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(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 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)
+}

pkg/attestation/attestation_test.go

@@ -0,0 +1,18 @@
+package attestation_test
+
+import (
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/attestation"
+	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.UnsignedTestImage, intoto.PayloadType)
+	assert.NoError(t, err)
+	assert.Equalf(t, len(statements), ExpectedStatements, "expected %d statement, got %d", ExpectedStatements, len(statements))
+}

pkg/attestation/example_attestation_manifest_test.go

@@ -0,0 +1,89 @@
+package attestation_test
+
+import (
+	"context"
+	"time"
+
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/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{
+		SkipTL: true, // skip trust logging to a transparency log
+	}
+
+	ref := "docker/image-signer-verifier:latest"
+
+	digest, err := v1.NewHash("sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620")
+	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)
+	}
+	err = oci.SaveImagesNoTag(artifacts, output)
+	if err != nil {
+		panic(err)
+	}
+}

pkg/attestation/layout.go

@@ -0,0 +1,147 @@
+package attestation
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/docker/attest/pkg/oci"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+)
+
+// implementation of Resolver that closes over attestations from an oci layout.
+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) ([]*Envelope, error) {
+	var envs []*Envelope
+	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(Envelope)
+		// parse layer blob as json
+		r, err := attestationLayer.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 *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) {
+	idx, err := layout.ImageIndexFromPath(path)
+	if err != nil {
+		return nil, err
+	}
+
+	idxm, err := idx.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get digest: %w", err)
+	}
+
+	idxDescriptor := idxm.Manifests[0]
+	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)
+	}
+	var subjectDescriptor *v1.Descriptor
+	for i := range mfs2.Manifests {
+		manifest := &mfs2.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 mfs2.Manifests {
+		mf := &mfs2.Manifests[i]
+		if mf.Annotations[DockerReferenceType] != AttestationManifestType {
+			continue
+		}
+
+		if mf.Annotations[DockerReferenceDigest] != subjectDescriptor.Digest.String() {
+			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)
+		}
+		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:        idxDescriptor.Annotations["org.opencontainers.image.ref.name"],
+			SubjectDescriptor:  subjectDescriptor,
+		}
+		return attest, nil
+	}
+	return nil, fmt.Errorf("attestation manifest not found")
+}

pkg/attestation/layout_test.go

@@ -0,0 +1,68 @@
+package attestation_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/attest"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/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.UnsignedTestImage)
+	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([]*oci.ImageSpec{spec}, signedIndex, outputLayout)
+	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:"))
+		})
+	}
+}

pkg/attestation/mock.go

@@ -0,0 +1,50 @@
+package attestation
+
+import (
+	"context"
+
+	"github.com/docker/attest/pkg/oci"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+)
+
+type MockResolver struct {
+	Envs []*Envelope
+}
+
+func (r MockResolver) Attestations(_ context.Context, _ string) ([]*Envelope, error) {
+	return r.Envs, nil
+}
+
+func (r MockResolver) ImageName(_ context.Context) (string, error) {
+	return "library/alpine:latest", nil
+}
+
+func (r MockResolver) ImageDescriptor(_ context.Context) (*v1.Descriptor, error) {
+	digest, err := v1.NewHash("sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620")
+	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) {
+	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
+}

pkg/attestation/referrers.go

@@ -0,0 +1,123 @@
+package attestation
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/docker/attest/pkg/oci"
+	"github.com/google/go-containerregistry/pkg/name"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+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) ([]*Envelope, error) {
+	manifests, err := r.resolveAttestations(ctx, predicateType)
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve attestations: %w", err)
+	}
+	var envs []*Envelope
+	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
+}

pkg/attestation/referrers_test.go

@@ -0,0 +1,329 @@
+package attestation_test
+
+import (
+	"fmt"
+	"net/http/httptest"
+	"net/url"
+	"path/filepath"
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/attest"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/config"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/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 config.AttestationStyle
+		expectFailure     bool
+	}{
+		{
+			name:   "referrers support, defaults",
+			server: httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+		},
+		{
+			name:      "use digest",
+			server:    httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			useDigest: true,
+		},
+		{
+			name:              "attached attestations, referrers repo (mismatched args)",
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			expectFailure:     true, // mismatched args
+			attestationSource: config.AttestationStyleAttached,
+			referrersRepo:     "referrers",
+		},
+		{
+			name:              "referrers attestations, referrers repo (no policy)",
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			expectFailure:     true, // no policy
+			attestationSource: config.AttestationStyleReferrers,
+			referrersRepo:     "referrers",
+		},
+		{
+			name:              "referrers attestations",
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			attestationSource: config.AttestationStyleReferrers,
+		},
+		{
+			name:              "referrers attestations, no referrers support on server",
+			server:            httptest.NewServer(registry.New(registry.WithReferrersSupport(false))),
+			attestationSource: config.AttestationStyleReferrers,
+			referrersServer:   httptest.NewServer(registry.New(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{
+				SkipTL: true,
+			}
+			attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+			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(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(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:    httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+			refServer: httptest.NewServer(registry.New(registry.WithReferrersSupport(true))),
+		},
+		{
+			name:      "no referrers support",
+			server:    httptest.NewServer(registry.New()),
+			refServer: httptest.NewServer(registry.New(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{
+			SkipTL: true,
+		}
+		attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+		require.NoError(t, err)
+
+		indexName := fmt.Sprintf("%s/%s:latest", serverURL.Host, repoName)
+		err = oci.PushIndexToRegistry(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(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{
+				SkipTL: true,
+			}
+			attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+			require.NoError(t, err)
+
+			indexName := fmt.Sprintf("%s/%s:latest", serverURL.Host, repoName)
+			err = oci.PushIndexToRegistry(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(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)
+	server := httptest.NewServer(registry.New())
+
+	defer server.Close()
+	serverURL, err := url.Parse(server.URL)
+	require.NoError(t, err)
+
+	repoName := "repo"
+
+	opts := &attestation.SigningOptions{
+		SkipTL: true,
+	}
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+	require.NoError(t, err)
+
+	indexName := fmt.Sprintf("%s/%s:latest", serverURL.Host, repoName)
+	err = oci.PushIndexToRegistry(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(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)
+			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")
+			}
+		}
+	}
+}

pkg/attestation/registry.go

@@ -0,0 +1,101 @@
+package attestation
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/docker/attest/pkg/oci"
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/remote"
+)
+
+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) ([]*Envelope, 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
+}

pkg/attestation/registry_test.go

@@ -0,0 +1,50 @@
+package attestation_test
+
+import (
+	"fmt"
+	"net/http/httptest"
+	"net/url"
+	"strings"
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/attest"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/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)
+	server := httptest.NewServer(registry.New(registry.WithReferrersSupport(false)))
+	defer server.Close()
+	u, err := url.Parse(server.URL)
+	require.NoError(t, err)
+
+	opts := &attestation.SigningOptions{}
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+	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(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:"))
+}

pkg/attestation/resolver.go

@@ -0,0 +1,12 @@
+package attestation
+
+import (
+	"context"
+
+	"github.com/docker/attest/pkg/oci"
+)
+
+type Resolver interface {
+	oci.ImageDetailsResolver
+	Attestations(ctx context.Context, mediaType string) ([]*Envelope, error)
+}

pkg/attestation/sign.go

@@ -0,0 +1,77 @@
+package attestation
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/docker/attest/internal/util"
+	"github.com/docker/attest/pkg/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.SkipTL {
+		ext, err := logSignature(ctx, tlog.GetTL(ctx), &sig, &encPayload, signer)
+		if err != nil {
+			return nil, fmt.Errorf("failed to log to rekor: %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.TL, 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.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)
+	}
+	return &Extension{
+		Kind: DockerDSSEExtKind,
+		Ext: &DockerDSSEExtension{
+			TL: &DockerTLExtension{
+				Kind: RekorTLExtKind,
+				Data: entryObj, // transparency log entry metadata
+			},
+		},
+	}, nil
+}

pkg/attestation/sign_test.go

@@ -0,0 +1,301 @@
+package attestation_test
+
+import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"encoding/json"
+	"fmt"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+	"time"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/signerverifier"
+	"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)
+	opts := &attestation.SigningOptions{}
+	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},
+			}
+			_, err = attestation.VerifyDSSE(ctx, deserializedEnv, opts)
+			if tc.expectedError != "" {
+				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("sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620")
+			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)
+			}
+			server := httptest.NewServer(registry.New(registry.WithReferrersSupport(true)))
+			defer server.Close()
+
+			u, err := url.Parse(server.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(artifacts, output)
+			require.NoError(t, err)
+		})
+	}
+}

pkg/attestation/types.go

@@ -0,0 +1,113 @@
+package attestation
+
+import (
+	"encoding/base64"
+	"fmt"
+
+	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"
+	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"
+	RekorTLExtKind                = "Rekor"
+	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 AnnotatedStatement struct {
+	OCIDescriptor   *v1.Descriptor
+	InTotoStatement *intoto.Statement
+	Annotations     map[string]string
+}
+
+type DockerDSSEExtension struct {
+	TL *DockerTLExtension `json:"tl"`
+}
+
+type DockerTLExtension struct {
+	Kind string `json:"kind"`
+	Data any    `json:"data"`
+}
+
+type VerifyOptions struct {
+	Keys   []*KeyMetadata `json:"keys"`
+	SkipTL bool           `json:"skip_tl"`
+}
+
+type SigningOptions struct {
+	// don't log to the configured transparency log
+	SkipTL bool
+}
+
+type Options struct {
+	NoReferrers   bool
+	Attach        bool
+	ReferrersRepo string
+}
+
+func DSSEMediaType(predicateType string) (string, error) {
+	var predicateName string
+	switch predicateType {
+	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
+}

pkg/attestation/verify.go

@@ -0,0 +1,138 @@
+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
+	KeysMap map[string]*KeyMetadata
+)
+
+func VerifyDSSE(ctx context.Context, 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")
+	}
+
+	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, opts)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return payload, nil
+}
+
+func verifySignature(ctx context.Context, sig *Signature, payload []byte, opts *VerifyOptions) error {
+	keys := make(map[string]*KeyMetadata, len(opts.Keys))
+	for _, key := range opts.Keys {
+		keys[key.ID] = key
+	}
+	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)
+	}
+	// TODO: this is unmarshalling with MarshalPKIXPublicKey only for us to marshal it again
+	publicKey, err := signerverifier.ParsePublicKey([]byte(keyMeta.PEM))
+	if err != nil {
+		return fmt.Errorf("failed to parse public key: %w", err)
+	}
+
+	if !opts.SkipTL {
+		t := tlog.GetTL(ctx)
+		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)
+		}
+
+		// 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)
+		}
+		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)
+		}
+		// 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.SHA256(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/attestation/verify_test.go

@@ -0,0 +1,49 @@
+package attestation_test
+
+import (
+	"encoding/base64"
+	"testing"
+
+	"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"
+)
+
+func TestValidPayloadType(t *testing.T) {
+	testCases := []struct {
+		name        string
+		payloadType string
+		expected    bool
+	}{
+		{"valid in-toto payload type", intoto.PayloadType, true},
+		{"valid oci descriptor payload type", ociv1.MediaTypeDescriptor, true},
+		{"invalid payload type", "application/vnd.test.fail", false},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equalf(t, tc.expected, attestation.ValidPayloadType(tc.payloadType), "expected %v for payload type %s", tc.expected, tc.payloadType)
+		})
+	}
+}
+
+func TestVerifyUnsignedAttestation(t *testing.T) {
+	ctx, _ := test.Setup(t)
+
+	payload := []byte("payload")
+	env := &attestation.Envelope{
+		// no signatures
+		Signatures:  []*attestation.Signature{},
+		Payload:     base64.StdEncoding.EncodeToString(payload),
+		PayloadType: intoto.PayloadType,
+	}
+	opts := &attestation.VerifyOptions{
+		Keys: attestation.Keys{},
+	}
+
+	_, err := attestation.VerifyDSSE(ctx, env, opts)
+	assert.Error(t, err)
+	assert.Contains(t, err.Error(), "no signatures")
+}

pkg/attestation/vsa.go

@@ -0,0 +1,51 @@
+package attestation
+
+import (
+	"fmt"
+
+	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  []VSAInputAttestation `json:"inputAttestations,omitempty"`
+	VerificationResult string                `json:"verificationResult"`
+	VerifiedLevels     []string              `json:"verifiedLevels"`
+}
+
+type VSAVerifier struct {
+	ID string `json:"id"`
+}
+
+type VSAPolicy struct {
+	URI              string            `json:"uri,omitempty"`
+	Digest           map[string]string `json:"digest"`
+	DownloadLocation string            `json:"downloadLocation,omitempty"`
+}
+
+type VSAInputAttestation struct {
+	Digest    map[string]string `json:"digest"`
+	MediaType string            `json:"mediaType"`
+}
+
+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
+}

pkg/config/config.go

@@ -0,0 +1,77 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+
+	"github.com/docker/attest/pkg/tuf"
+	"sigs.k8s.io/yaml"
+)
+
+const (
+	MappingFilename = "mapping.yaml"
+)
+
+func LoadLocalMappings(configDir string) (*PolicyMappings, error) {
+	if configDir == "" {
+		return nil, nil
+	}
+	mappings := &policyMappingsFile{}
+	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)
+	}
+	err = yaml.Unmarshal(mappingFile, mappings)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal policy mapping file %s: %w", path, err)
+	}
+	return expandMappingFile(mappings)
+}
+
+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)
+	}
+	mappings := &policyMappingsFile{}
+
+	err = yaml.Unmarshal(file.Data, mappings)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal policy mapping file %s: %w", filename, err)
+	}
+	return expandMappingFile(mappings)
+}
+
+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 {
+		r, err := regexp.Compile(rule.Pattern)
+		if err != nil {
+			return nil, err
+		}
+		rules = append(rules, &PolicyRule{
+			Pattern:     r,
+			PolicyID:    rule.PolicyID,
+			Replacement: rule.Replacement,
+		})
+	}
+
+	return &PolicyMappings{
+		Version:  mappingFile.Version,
+		Kind:     mappingFile.Kind,
+		Policies: policies,
+		Rules:    rules,
+	}, nil
+}

pkg/config/types.go

@@ -0,0 +1,54 @@
+package config
+
+import (
+	"regexp"
+)
+
+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"`
+	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
+}

pkg/mirror/README.md

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

pkg/mirror/example_mirror_test.go

@@ -0,0 +1,152 @@
+package mirror_test
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/docker/attest/pkg/mirror"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/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"
+	m, err := mirror.NewTUFMirror(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(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(o *TufMirrorOutput) error {
+	// push metadata to registry
+	metadataRepo := "registry-1.docker.io/docker/tuf-metadata:latest"
+	err := oci.PushImageToRegistry(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(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(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(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
+}

pkg/mirror/metadata.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"strconv"
 
+	"github.com/docker/attest/pkg/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 +17,9 @@ 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 +27,19 @@ 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 +70,7 @@ 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 +78,27 @@ 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 +109,19 @@ 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 +130,8 @@ 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 +144,12 @@ 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 +166,15 @@ 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 +184,7 @@ 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
 }

pkg/mirror/metadata_test.go

@@ -9,22 +9,27 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/docker/attest/internal/embed"
 	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/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("..", "..", "internal", "test", "testdata", "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(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 +39,19 @@ func TestGetTufMetadataMirror(t *testing.T) {
 }
 
 func TestGetMetadataManifest(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "internal", "test", "testdata", "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(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 +61,7 @@ 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 +73,20 @@ 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("..", "..", "internal", "test", "testdata", "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(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)

pkg/mirror/mirror.go

@@ -2,81 +2,17 @@ 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) {
+func NewTUFMirror(root []byte, tufPath, metadataURL, targetsURL string, versionChecker tuf.VersionChecker) (*TUFMirror, error) {
 	if root == nil {
-		root = embed.DefaultRoot
+		root = tuf.DockerTUFRootDefault.Data
 	}
-	tufClient, err := tuf.NewTufClient(root, tufPath, metadataURL, targetsURL)
+	tufClient, err := tuf.NewClient(&tuf.ClientOptions{InitialRoot: root, Path: 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
-}
-
-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
+	return &TUFMirror{TUFClient: tufClient, tufPath: tufPath, metadataURL: metadataURL, targetsURL: targetsURL}, nil
 }

pkg/mirror/targets.go

@@ -5,6 +5,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	"github.com/docker/attest/pkg/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 +14,16 @@ 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 +36,23 @@ 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 +61,7 @@ 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 +69,7 @@ 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 +87,17 @@ 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 +105,7 @@ 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
 }

pkg/mirror/targets_test.go

@@ -8,8 +8,8 @@ import (
 	"strings"
 	"testing"
 
-	"github.com/docker/attest/internal/embed"
 	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/tuf"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -22,82 +22,82 @@ type Layers struct {
 }
 
 func TestGetTufTargetsMirror(t *testing.T) {
-	server := httptest.NewServer(http.FileServer(http.Dir(filepath.Join("..", "..", "internal", "test", "testdata", "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(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("..", "..", "internal", "test", "testdata", "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(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("..", "..", "internal", "test", "testdata", "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(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)
 		}
 	}
 }

pkg/mirror/types.go

@@ -1,24 +1,25 @@
 package mirror
 
 import (
+	"github.com/docker/attest/pkg/oci"
 	"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"
+	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
+type TUFRole string
 
-var TufRoles = []TufRole{metadata.ROOT, metadata.SNAPSHOT, metadata.TARGETS, metadata.TIMESTAMP}
+var TUFRoles = []TUFRole{metadata.ROOT, metadata.SNAPSHOT, metadata.TARGETS, metadata.TIMESTAMP}
 
-type TufMetadata struct {
+type TUFMetadata struct {
 	Root      map[string][]byte
 	Snapshot  map[string][]byte
 	Targets   map[string][]byte
@@ -31,18 +32,18 @@ type DelegatedTargetMetadata struct {
 	Data    []byte
 }
 
-type MirrorImage struct {
-	Image *v1.Image
+type Image struct {
+	Image *oci.EmptyConfigImage
 	Tag   string
 }
 
-type MirrorIndex struct {
-	Index *v1.ImageIndex
+type Index struct {
+	Index v1.ImageIndex
 	Tag   string
 }
 
-type TufMirror struct {
-	TufClient   *tuf.TufClient
+type TUFMirror struct {
+	TUFClient   *tuf.Client
 	tufPath     string
 	metadataURL string
 	targetsURL  string

pkg/oci/README.md

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

pkg/oci/authn.go

@@ -0,0 +1,21 @@
+package oci
+
+import (
+	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()),
+	)
+}

pkg/oci/authn_test.go

@@ -0,0 +1,31 @@
+//go:build e2e
+
+package oci_test
+
+import (
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRegistryAuth(t *testing.T) {
+	attIdx, err := oci.IndexFromPath(test.UnsignedTestImage)
+	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"},
+	}
+	for _, tc := range testCases {
+		t.Run(tc.Image, func(t *testing.T) {
+			err := oci.PushIndexToRegistry(attIdx.Index, tc.Image)
+			require.NoError(t, err)
+			_, err = oci.IndexFromRemote(tc.Image)
+			require.NoError(t, err)
+		})
+	}
+}

pkg/oci/http.go

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

pkg/oci/oci.go

@@ -0,0 +1,149 @@
+package oci
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/containerd/platforms"
+	"github.com/distribution/reference"
+	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.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 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("docker", 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
+}

pkg/oci/oci_test.go

@@ -0,0 +1,146 @@
+package oci_test
+
+import (
+	"testing"
+
+	"github.com/distribution/reference"
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/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.UnsignedTestImage)
+	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, "sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620", 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, "sha256:7a76cec943853f9f7105b1976afa1bf7cd5bb6afc4e9d5852dd8da7cf81ae86e", 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)
+		})
+	}
+}

pkg/oci/output.go

@@ -0,0 +1,144 @@
+package oci
+
+import (
+	"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(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, MultiKeychainOption())
+}
+
+// PushIndexToRegistry pushes an index to the registry with the specified name.
+func PushIndexToRegistry(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, MultiKeychainOption())
+}
+
+// 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(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(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(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(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(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(image, spec.Identifier)
+			if err != nil {
+				return fmt.Errorf("failed to push image: %w", err)
+			}
+		}
+	}
+	return nil
+}

pkg/oci/output_test.go

@@ -0,0 +1,109 @@
+package oci_test
+
+import (
+	"fmt"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/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.UnsignedTestImage)
+	require.NoError(t, err)
+
+	server := httptest.NewServer(registry.New())
+	defer server.Close()
+
+	u, err := url.Parse(server.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(output, attIdx.Index, indexName)
+	require.NoError(t, err)
+
+	ociOutput, err := oci.ParseImageSpecs(oci.LocalPrefix + outputLayout)
+	require.NoError(t, err)
+	err = oci.SaveIndex(ociOutput, attIdx.Index, indexName)
+	require.NoError(t, err)
+}
+
+func TestSavingImage(t *testing.T) {
+	outputLayout := test.CreateTempDir(t, "", "mirror-test")
+
+	img := empty.Image
+
+	server := httptest.NewServer(registry.New())
+	defer server.Close()
+
+	u, err := url.Parse(server.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(output, img, indexName)
+	require.NoError(t, err)
+
+	ociOutput, err := oci.ParseImageSpec(oci.LocalPrefix + outputLayout)
+	require.NoError(t, err)
+	err = oci.SaveImage(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("sha256:da8b190665956ea07890a0273e2a9c96bfe291662f08e2860e868eef69c34620")
+	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)
+	server := httptest.NewServer(registry.New(registry.WithReferrersSupport(true)))
+	defer server.Close()
+
+	u, err := url.Parse(server.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(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)
+}

pkg/oci/registry.go

@@ -0,0 +1,61 @@
+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"
+)
+
+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
+}

pkg/oci/resolver.go

@@ -0,0 +1,13 @@
+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)
+}

pkg/oci/types.go

@@ -0,0 +1,217 @@
+package oci
+
+import (
+	"bytes"
+	"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(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, MultiKeychainOption())
+	if err != nil {
+		return nil, fmt.Errorf("failed to pull image %s: %w", image, err)
+	}
+	return &NamedIndex{
+		Index: idx,
+		Name:  image,
+	}, nil
+}
+
+func LoadIndex(input *ImageSpec) (*NamedIndex, error) {
+	if input.Type == OCI {
+		return IndexFromPath(input.Identifier)
+	}
+	return IndexFromRemote(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
+}

pkg/oci/types_test.go

@@ -0,0 +1,21 @@
+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/policy/README.md

@@ -0,0 +1,2 @@
+## policy
+This package is for attestation policy mapping and evaluation.

pkg/policy/evaluator.go

@@ -0,0 +1,11 @@
+package policy
+
+import (
+	"context"
+
+	"github.com/docker/attest/pkg/attestation"
+)
+
+type Evaluator interface {
+	Evaluate(ctx context.Context, resolver attestation.Resolver, pctx *Policy, input *Input) (*Result, error)
+}

pkg/policy/match.go

@@ -0,0 +1,65 @@
+package policy
+
+import (
+	"fmt"
+
+	"github.com/docker/attest/pkg/config"
+)
+
+type matchType string
+
+const (
+	matchTypePolicy        matchType = "policy"
+	matchTypeMatchNoPolicy matchType = "match_no_policy"
+	matchTypeNoMatch       matchType = "no_match"
+)
+
+type policyMatch struct {
+	matchType   matchType
+	policy      *config.PolicyMapping
+	rule        *config.PolicyRule
+	matchedName string
+}
+
+func findPolicyMatch(imageName string, mappings *config.PolicyMappings) (*policyMatch, error) {
+	if mappings == nil {
+		return &policyMatch{matchType: matchTypeNoMatch, matchedName: imageName}, nil
+	}
+	return findPolicyMatchImpl(imageName, mappings, make(map[*config.PolicyRule]bool))
+}
+
+func findPolicyMatchImpl(imageName string, mappings *config.PolicyMappings, matched map[*config.PolicyRule]bool) (*policyMatch, error) {
+	for _, rule := range mappings.Rules {
+		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 findPolicyMatchImpl(imageName, mappings, matched)
+			}
+		}
+	}
+	return &policyMatch{matchType: matchTypeNoMatch, matchedName: imageName}, nil
+}

pkg/policy/match_test.go

@@ -0,0 +1,121 @@
+package policy
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/docker/attest/pkg/config"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFindPolicyMatch(t *testing.T) {
+	testCases := []struct {
+		name       string
+		imageName  string
+		mappingDir string
+
+		expectError       bool
+		expectedMatchType matchType
+		expectedPolicyID  string
+		expectedImageName 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,
+			expectedImageName: "docker.io/something/else",
+		},
+		{
+			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,
+			expectedImageName: "badredirect.org/alpine",
+		},
+		{
+			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:       "invalid rewrites",
+			mappingDir: "rewrite-invalid",
+			imageName:  "mycoolmirror.org/library/alpine",
+
+			expectError:       true,
+			expectedMatchType: matchTypePolicy,
+			expectedPolicyID:  "docker-official-images",
+			expectedImageName: "docker.io/library/alpine",
+		},
+		{
+			name:       "rewrite loop",
+			mappingDir: "rewrite-loop",
+			imageName:  "yin/alpine",
+
+			expectError: true,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			mappings, err := config.LoadLocalMappings(filepath.Join("testdata", "mappings", tc.mappingDir))
+			require.NoError(t, err)
+			match, err := findPolicyMatch(tc.imageName, mappings)
+			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)
+				}
+			}
+			assert.Equal(t, tc.expectedImageName, match.matchedName)
+		})
+	}
+}

pkg/policy/mock.go

@@ -0,0 +1,32 @@
+package policy
+
+import (
+	"context"
+
+	"github.com/docker/attest/pkg/attestation"
+)
+
+type MockPolicyEvaluator struct {
+	EvaluateFunc func(ctx context.Context, resolver attestation.Resolver, pctx *Policy, input *Input) (*Result, error)
+}
+
+func (pe *MockPolicyEvaluator) Evaluate(ctx context.Context, resolver attestation.Resolver, pctx *Policy, input *Input) (*Result, error) {
+	if pe.EvaluateFunc != nil {
+		return pe.EvaluateFunc(ctx, resolver, pctx, input)
+	}
+	return AllowedResult(), nil
+}
+
+func GetMockPolicy() Evaluator {
+	return &MockPolicyEvaluator{
+		EvaluateFunc: func(_ context.Context, _ attestation.Resolver, _ *Policy, _ *Input) (*Result, error) {
+			return AllowedResult(), nil
+		},
+	}
+}
+
+func AllowedResult() *Result {
+	return &Result{
+		Success: true,
+	}
+}

pkg/policy/policy.go

@@ -0,0 +1,38 @@
+package policy
+
+import (
+	"fmt"
+
+	"github.com/docker/attest/pkg/attestation"
+	"github.com/docker/attest/pkg/config"
+	"github.com/docker/attest/pkg/oci"
+)
+
+func CreateImageDetailsResolver(imageSource *oci.ImageSpec) (oci.ImageDetailsResolver, error) {
+	switch imageSource.Type {
+	case oci.OCI:
+		return attestation.NewOCILayoutResolver(imageSource)
+	case oci.Docker:
+		return oci.NewRegistryImageDetailsResolver(imageSource)
+	}
+	return nil, fmt.Errorf("unsupported image source type: %s", imageSource.Type)
+}
+
+func CreateAttestationResolver(resolver oci.ImageDetailsResolver, mapping *config.PolicyMapping) (attestation.Resolver, error) {
+	if mapping.Attestations != nil {
+		if mapping.Attestations.Style == config.AttestationStyleAttached {
+			switch resolver := resolver.(type) {
+			case *oci.RegistryImageDetailsResolver:
+				return attestation.NewRegistryResolver(resolver)
+			case *attestation.LayoutResolver:
+				return resolver, nil
+			default:
+				return nil, fmt.Errorf("unsupported image details resolver type: %T", resolver)
+			}
+		}
+		if mapping.Attestations.Repo != "" {
+			return attestation.NewReferrersResolver(resolver, attestation.WithReferrersRepo(mapping.Attestations.Repo))
+		}
+	}
+	return attestation.NewReferrersResolver(resolver)
+}

pkg/policy/policy_test.go

@@ -0,0 +1,175 @@
+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/config"
+	"github.com/docker/attest/pkg/oci"
+	"github.com/docker/attest/pkg/policy"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func loadAttestation(t *testing.T, path string) *attestation.Envelope {
+	ex, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	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)
+	resolveErrorStr := "failed to resolve policy by id: policy with id non-existent-policy-id not found"
+	TestDataPath := filepath.Join("..", "..", "test", "testdata")
+	ExampleAttestation := filepath.Join(TestDataPath, "example_attestation.json")
+
+	re := policy.NewRegoEvaluator(true)
+
+	defaultResolver := attestation.MockResolver{
+		Envs: []*attestation.Envelope{loadAttestation(t, ExampleAttestation)},
+	}
+
+	testCases := []struct {
+		policyPath      string
+		expectSuccess   bool
+		isCanonical     bool
+		resolver        attestation.Resolver
+		opts            *policy.Options
+		policyID        string
+		resolveErrorStr string
+	}{
+		{policyPath: "testdata/policies/allow", expectSuccess: true, resolver: defaultResolver},
+		{policyPath: "testdata/policies/allow", expectSuccess: true, resolver: defaultResolver, policyID: "docker-official-images"},
+		{policyPath: "testdata/policies/allow", resolver: defaultResolver, policyID: "non-existent-policy-id", resolveErrorStr: resolveErrorStr},
+		{policyPath: "testdata/policies/deny", resolver: defaultResolver},
+		{policyPath: "testdata/policies/verify-sig", expectSuccess: true, resolver: defaultResolver},
+		{policyPath: "testdata/policies/wrong-key", resolver: defaultResolver},
+		{policyPath: "testdata/policies/allow-canonical", expectSuccess: true, isCanonical: true, resolver: defaultResolver},
+		{policyPath: "testdata/policies/allow-canonical", resolver: defaultResolver},
+		{policyPath: "testdata/policies/no-rego", resolver: defaultResolver, resolveErrorStr: "no policy file found in policy mapping"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.policyPath, func(t *testing.T) {
+			input := &policy.Input{
+				Digest: "sha256:test-digest",
+				PURL:   "test-purl",
+			}
+			if !tc.isCanonical {
+				input.Tag = "test"
+			}
+
+			if tc.opts == nil {
+				tc.opts = &policy.Options{
+					LocalTargetsDir: test.CreateTempDir(t, "", "tuf-targets"),
+					PolicyID:        tc.policyID,
+					LocalPolicyDir:  tc.policyPath,
+					DisableTUF:      true,
+				}
+			}
+			imageName, err := tc.resolver.ImageName(ctx)
+			require.NoError(t, err)
+			resolver := policy.NewResolver(nil, tc.opts)
+			policy, err := resolver.ResolvePolicy(ctx, imageName)
+			if tc.resolveErrorStr != "" {
+				require.Error(t, err)
+				assert.Contains(t, err.Error(), tc.resolveErrorStr)
+				return
+			}
+			require.NoErrorf(t, err, "failed to resolve policy")
+			require.NotNil(t, policy, "policy should not be nil")
+			result, err := re.Evaluate(ctx, tc.resolver, policy, input)
+			require.NoErrorf(t, err, "Evaluate failed")
+
+			if tc.expectSuccess {
+				assert.True(t, result.Success, "Evaluate should have succeeded")
+			} else {
+				assert.False(t, result.Success, "Evaluate should have failed")
+			}
+		})
+	}
+}
+
+func TestLoadingMappings(t *testing.T) {
+	policyMappings, err := config.LoadLocalMappings(filepath.Join("testdata", "policies", "allow"))
+	require.NoError(t, err)
+	assert.Equal(t, len(policyMappings.Rules), 3)
+	for _, mirror := range policyMappings.Rules {
+		if mirror.PolicyID != "" {
+			assert.Equal(t, "docker-official-images", mirror.PolicyID)
+		}
+	}
+}
+
+func TestCreateAttestationResolver(t *testing.T) {
+	mockResolver := attestation.MockResolver{
+		Envs: []*attestation.Envelope{},
+	}
+	layoutResolver := &attestation.LayoutResolver{}
+	registryResolver := &oci.RegistryImageDetailsResolver{}
+
+	nilRepoReferrers := &config.PolicyMapping{
+		Attestations: &config.AttestationConfig{
+			Style: config.AttestationStyleReferrers,
+		},
+	}
+	referrers := &config.PolicyMapping{
+		Attestations: &config.AttestationConfig{
+			Repo:  "localhost:5000/repo",
+			Style: config.AttestationStyleReferrers,
+		},
+	}
+	attached := &config.PolicyMapping{
+		Attestations: &config.AttestationConfig{
+			Style: config.AttestationStyleAttached,
+		},
+	}
+
+	testCases := []struct {
+		name     string
+		resolver oci.ImageDetailsResolver
+		mapping  *config.PolicyMapping
+		errorStr string
+	}{
+		{name: "referrers", resolver: layoutResolver, mapping: referrers},
+		{name: "referrers (no mapped repo)", resolver: layoutResolver, mapping: nilRepoReferrers},
+		{name: "referrers (no mapping)", resolver: layoutResolver, mapping: &config.PolicyMapping{Attestations: nil}},
+		{name: "attached (registry)", resolver: registryResolver, mapping: attached},
+		{name: "attached (layout)", resolver: layoutResolver, mapping: attached},
+		{name: "attached (unsupported)", resolver: mockResolver, mapping: attached, errorStr: "unsupported image details resolver type"},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			resolver, err := policy.CreateAttestationResolver(tc.resolver, tc.mapping)
+			if tc.errorStr == "" {
+				require.NoError(t, err)
+			} else {
+				assert.Contains(t, err.Error(), tc.errorStr)
+			}
+			if tc.mapping.Attestations == nil {
+				return
+			}
+			switch resolver.(type) {
+			case *attestation.ReferrersResolver:
+				assert.Equal(t, tc.mapping.Attestations.Style, config.AttestationStyleReferrers)
+			case *attestation.RegistryResolver:
+				assert.Equal(t, tc.mapping.Attestations.Style, config.AttestationStyleAttached)
+			case *attestation.LayoutResolver:
+				assert.Equal(t, tc.mapping.Attestations.Style, config.AttestationStyleAttached)
+			}
+		})
+	}
+}

pkg/policy/rego.go

@@ -0,0 +1,277 @@
+package policy
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/docker/attest/pkg/attestation"
+	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
+}
+
+const (
+	DefaultQuery  = "result := data.attest.result"
+	resultBinding = "result"
+)
+
+func NewRegoEvaluator(debug bool) Evaluator {
+	return &regoEvaluator{
+		debug: debug,
+	}
+}
+
+func (re *regoEvaluator) Evaluate(ctx context.Context, resolver attestation.Resolver, pctx *Policy, input *Input) (*Result, 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 nil, err
+	}
+
+	for _, target := range pctx.InputFiles {
+		// 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 nil, err
+			}
+			err = store.Write(ctx, txn, storage.AddOp, storage.Path{}, yamlData)
+			if err != nil {
+				return nil, 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 nil, err
+	}
+
+	if re.debug {
+		regoOpts = append(regoOpts,
+			rego.EnablePrintStatements(true),
+			rego.PrintHook(topdown.NewPrintHook(os.Stderr)),
+			rego.Dump(os.Stderr),
+		)
+	}
+	query := DefaultQuery
+	if pctx.Query != "" {
+		query = pctx.Query
+	}
+	regoOpts = append(regoOpts,
+		rego.Query(query),
+		rego.Input(input),
+		rego.Store(store),
+		rego.GenerateJSON(jsonGenerator[Result]()),
+	)
+	for _, custom := range RegoFunctions(resolver) {
+		regoOpts = append(regoOpts, custom.Func)
+	}
+
+	r := rego.New(regoOpts...)
+	rs, err := r.Eval(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(rs) == 0 {
+		return nil, fmt.Errorf("no policy evaluation result")
+	}
+	binding, ok := rs[0].Bindings[resultBinding]
+	if !ok {
+		return nil, fmt.Errorf("failed to extract verification result")
+	}
+	result, ok := binding.(Result)
+	if !ok {
+		return nil, fmt.Errorf("failed to extract verification result")
+	}
+
+	return &result, nil
+}
+
+func jsonGenerator[T any]() func(t *ast.Term, ec *rego.EvalContext) (any, error) {
+	return func(t *ast.Term, _ *rego.EvalContext) (any, error) {
+		// TODO: this is horrible - we're converting the AST to JSON and then back to AST, then using ast.As to convert it to a struct
+		// We can't use ast.As directly because it fails if the AST contains a set
+		json, err := ast.JSON(t.Value)
+		if err != nil {
+			return nil, err
+		}
+		v, err := ast.InterfaceToValue(json)
+		if err != nil {
+			return nil, err
+		}
+		var result T
+		err = ast.As(v, &result)
+		if err != nil {
+			return nil, err
+		}
+		return result, nil
+	}
+}
+
+var dynamicObj = types.NewObject(nil, types.NewDynamicProperty(types.A, types.A))
+
+var verifyDecl = &ast.Builtin{
+	Name:             "attest.verify",
+	Decl:             types.NewFunction(types.Args(dynamicObj, dynamicObj), dynamicObj),
+	Nondeterministic: true,
+}
+
+var attestDecl = &ast.Builtin{
+	Name:             "attest.fetch",
+	Decl:             types.NewFunction(types.Args(types.S), dynamicObj),
+	Nondeterministic: true,
+}
+
+func wrapFunctionResult(value *ast.Term, err error) (*ast.Term, error) {
+	var terms [][2]*ast.Term
+	if err != nil {
+		terms = append(terms, [2]*ast.Term{ast.StringTerm("error"), ast.StringTerm(err.Error())})
+	}
+	if value != nil {
+		terms = append(terms, [2]*ast.Term{ast.StringTerm("value"), value})
+	}
+	return ast.ObjectTerm(terms...), nil
+}
+
+func handleErrors1(f func(rCtx rego.BuiltinContext, a *ast.Term) (*ast.Term, error)) rego.Builtin1 {
+	return func(rCtx rego.BuiltinContext, a *ast.Term) (*ast.Term, error) {
+		return wrapFunctionResult(f(rCtx, a))
+	}
+}
+
+func handleErrors2(f func(rCtx *rego.BuiltinContext, a, b *ast.Term) (*ast.Term, error)) rego.Builtin2 {
+	return func(rCtx rego.BuiltinContext, a, b *ast.Term) (*ast.Term, error) {
+		return wrapFunctionResult(f(&rCtx, a, b))
+	}
+}
+
+func RegoFunctions(resolver attestation.Resolver) []*tester.Builtin {
+	return []*tester.Builtin{
+		{
+			Decl: verifyDecl,
+			Func: rego.Function2(
+				&rego.Function{
+					Name:             verifyDecl.Name,
+					Decl:             verifyDecl.Decl,
+					Memoize:          true,
+					Nondeterministic: verifyDecl.Nondeterministic,
+				},
+				handleErrors2(verifyInTotoEnvelope)),
+		},
+		{
+			Decl: attestDecl,
+			Func: rego.Function1(
+				&rego.Function{
+					Name:             attestDecl.Name,
+					Decl:             attestDecl.Decl,
+					Memoize:          true,
+					Nondeterministic: attestDecl.Nondeterministic,
+				},
+				handleErrors1(fetchInTotoAttestations(resolver))),
+		},
+	}
+}
+
+func fetchInTotoAttestations(resolver attestation.Resolver) rego.Builtin1 {
+	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.Set and convert it to an ast.Term.
+		set := ast.NewTerm(ast.NewSet(values...))
+
+		return set, nil
+	}
+}
+
+func verifyInTotoEnvelope(rCtx *rego.BuiltinContext, envTerm, optsTerm *ast.Term) (*ast.Term, error) {
+	env := new(attestation.Envelope)
+	opts := new(attestation.VerifyOptions)
+	err := ast.As(envTerm.Value, env)
+	if err != nil {
+		return nil, fmt.Errorf("failed to cast envelope: %w", err)
+	}
+	err = ast.As(optsTerm.Value, &opts)
+	if err != nil {
+		return nil, fmt.Errorf("failed to cast verifier options: %w", err)
+	}
+
+	payload, err := attestation.VerifyDSSE(rCtx.Context, env, opts)
+	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/resolver.go

@@ -0,0 +1,194 @@
+package policy
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"path"
+	"path/filepath"
+
+	"github.com/distribution/reference"
+	"github.com/docker/attest/internal/util"
+	"github.com/docker/attest/pkg/config"
+	"github.com/docker/attest/pkg/tuf"
+)
+
+type Resolver struct {
+	tufClient tuf.Downloader
+	opts      *Options
+}
+
+func NewResolver(tufClient tuf.Downloader, opts *Options) *Resolver {
+	return &Resolver{
+		tufClient: tufClient,
+		opts:      opts,
+	}
+}
+
+func (r *Resolver) ResolvePolicy(_ context.Context, imageName string) (*Policy, error) {
+	p, err := r.resolvePolicyByID()
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve policy by id: %w", err)
+	}
+	if p != nil {
+		return p, nil
+	}
+	imageName, err = normalizeImageName(imageName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to parse image name: %w", err)
+	}
+	localMappings, err := config.LoadLocalMappings(r.opts.LocalPolicyDir)
+	if err != nil {
+		return nil, fmt.Errorf("failed to load local policy mappings: %w", err)
+	}
+	match, err := findPolicyMatch(imageName, localMappings)
+	if err != nil {
+		return nil, err
+	}
+	if match.matchType == matchTypePolicy {
+		return r.resolveLocalPolicy(match.policy, imageName, match.matchedName)
+	}
+	if !r.opts.DisableTUF {
+		tufMappings, err := config.LoadTUFMappings(r.tufClient, r.opts.LocalTargetsDir)
+		if err != nil {
+			return nil, fmt.Errorf("failed to load tuf policy mappings as fallback: %w", err)
+		}
+
+		// it's a mirror of a tuf policy
+		if match.matchType == matchTypeMatchNoPolicy {
+			for _, mapping := range tufMappings.Policies {
+				if mapping.ID == match.rule.PolicyID {
+					return r.resolveTUFPolicy(mapping, imageName, match.matchedName)
+				}
+			}
+		}
+
+		// try to resolve a tuf policy directly
+		match, err = findPolicyMatch(imageName, tufMappings)
+		if err != nil {
+			return nil, err
+		}
+		if match.matchType == matchTypePolicy {
+			return r.resolveTUFPolicy(match.policy, imageName, match.matchedName)
+		}
+	}
+	return nil, nil
+}
+
+func (r *Resolver) resolveLocalPolicy(mapping *config.PolicyMapping, imageName string, matchedName string) (*Policy, error) {
+	if r.opts.LocalPolicyDir == "" {
+		return nil, fmt.Errorf("local policy dir not set")
+	}
+	var URI string
+	var digest map[string]string
+	files := make([]*File, 0, len(mapping.Files))
+	for _, f := range mapping.Files {
+		filename := f.Path
+		filePath := path.Join(r.opts.LocalPolicyDir, 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, &File{
+			Path:    filename,
+			Content: fileContents,
+		})
+		// if the file is a policy file, store the URI and digest
+		if filepath.Ext(filename) == ".rego" {
+			// TODO: support multiple rego files, need some way to identify the main policy file
+			if URI != "" {
+				return nil, fmt.Errorf("multiple policy files found in policy mapping")
+			}
+			URI = filePath
+			digest = map[string]string{"sha256": util.SHA256Hex(fileContents)}
+		}
+	}
+	if URI == "" {
+		return nil, fmt.Errorf("no policy file found in policy mapping")
+	}
+	policy := &Policy{
+		InputFiles: files,
+		Mapping:    mapping,
+		URI:        URI,
+		Digest:     digest,
+	}
+	if imageName != matchedName {
+		policy.ResolvedName = matchedName
+	}
+	return policy, nil
+}
+
+func (r *Resolver) resolveTUFPolicy(mapping *config.PolicyMapping, imageName string, matchedName string) (*Policy, error) {
+	var URI string
+	var digest map[string]string
+	files := make([]*File, 0, len(mapping.Files))
+	for _, f := range mapping.Files {
+		filename := f.Path
+		file, err := r.tufClient.DownloadTarget(filename, filepath.Join(r.opts.LocalTargetsDir, filename))
+		if err != nil {
+			return nil, fmt.Errorf("failed to download policy file %s: %w", filename, err)
+		}
+		files = append(files, &File{
+			Path:    filename,
+			Content: file.Data,
+		})
+		// if the file is a policy file, store the URI and digest
+		if filepath.Ext(filename) == ".rego" {
+			// TODO: support multiple rego files, need some way to identify the main policy file
+			if URI != "" {
+				return nil, fmt.Errorf("multiple policy files found in policy mapping")
+			}
+			URI = file.TargetURI
+			digest = map[string]string{"sha256": file.Digest}
+		}
+	}
+	if URI == "" {
+		return nil, fmt.Errorf("no policy file found in policy mapping")
+	}
+	policy := &Policy{
+		InputFiles: files,
+		Mapping:    mapping,
+		URI:        URI,
+		Digest:     digest,
+	}
+	if imageName != matchedName {
+		policy.ResolvedName = matchedName
+	}
+	return policy, nil
+}
+
+func (r *Resolver) resolvePolicyByID() (*Policy, error) {
+	if r.opts.PolicyID != "" {
+		localMappings, err := config.LoadLocalMappings(r.opts.LocalPolicyDir)
+		if err != nil {
+			return nil, fmt.Errorf("failed to load local policy mappings: %w", err)
+		}
+		if localMappings != nil {
+			policy := localMappings.Policies[r.opts.PolicyID]
+			if policy != nil {
+				return r.resolveLocalPolicy(policy, "", "")
+			}
+		}
+
+		if !r.opts.DisableTUF {
+			tufMappings, err := config.LoadTUFMappings(r.tufClient, r.opts.LocalTargetsDir)
+			if err != nil {
+				return nil, fmt.Errorf("failed to load tuf policy mappings by id: %w", err)
+			}
+			policy := tufMappings.Policies[r.opts.PolicyID]
+			if policy != nil {
+				return r.resolveTUFPolicy(policy, "", "")
+			}
+		}
+		return nil, fmt.Errorf("policy with id %s not found", r.opts.PolicyID)
+	}
+	return nil, nil
+}
+
+func normalizeImageName(imageName string) (string, error) {
+	named, err := reference.ParseNormalizedNamed(imageName)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse image name: %w", err)
+	}
+	return named.Name(), nil
+}

pkg/policy/resolver_test.go

@@ -0,0 +1,65 @@
+package policy_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/docker/attest/internal/test"
+	"github.com/docker/attest/pkg/policy"
+	"github.com/docker/attest/pkg/tuf"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestResolvePolicy(t *testing.T) {
+	localPolicyPath := "testdata/policies/allow"
+	tufPolicyPath := "testdata/policies/allow-canonical"
+	noLocalPolicyPath := "testdata/policies/no-policy"
+	testPolicyID := "docker-official-images"
+	testImageName := "localhost:5001/test/repo:tag"
+
+	testCases := []struct {
+		name              string
+		policyPath        string
+		policyID          string
+		localOverridesTUF bool // if a policy is provided locally, it should override TUF
+		DisableTUF        bool
+	}{
+		{name: "resolve by id (TUF only)", policyID: testPolicyID, DisableTUF: false},
+		{name: "resolve by id (local mapping, TUF policy)", policyPath: noLocalPolicyPath, policyID: testPolicyID, DisableTUF: false},
+		{name: "resolve by id (local mapping, local policy, no TUF)", policyPath: localPolicyPath, policyID: testPolicyID, DisableTUF: true},
+		{name: "resolve by id (local mapping, local policy)", policyPath: localPolicyPath, policyID: testPolicyID, DisableTUF: false, localOverridesTUF: true},
+		{name: "resolve by match (TUF only)", DisableTUF: false},
+		{name: "resolve by match (local mapping, TUF policy)", policyPath: noLocalPolicyPath, DisableTUF: false},
+		{name: "resolve by match (local mapping, local policy, no TUF)", policyPath: localPolicyPath, DisableTUF: true},
+		{name: "resolve by match (local mapping, local policy)", policyPath: localPolicyPath, DisableTUF: false, localOverridesTUF: true},
+	}
+
+	var tufClient tuf.Downloader
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			opts := &policy.Options{}
+			tempDir := test.CreateTempDir(t, "", "tuf-dest")
+			if !tc.DisableTUF {
+				tufClient = tuf.NewMockTufClient(tufPolicyPath)
+			}
+			if tc.policyID != "" {
+				opts.PolicyID = tc.policyID
+			}
+			if tc.policyPath != "" {
+				opts.LocalPolicyDir = tc.policyPath
+			}
+			opts.DisableTUF = tc.DisableTUF
+			opts.LocalTargetsDir = tempDir
+			resolver := policy.NewResolver(tufClient, opts)
+			policy, err := resolver.ResolvePolicy(context.Background(), testImageName)
+			require.NoError(t, err)
+			assert.NotNil(t, policy)
+			if tc.DisableTUF || tc.localOverridesTUF {
+				assert.Contains(t, policy.URI, localPolicyPath)
+			} else {
+				assert.Contains(t, policy.URI, tufPolicyPath)
+			}
+		})
+	}
+}

pkg/policy/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

pkg/policy/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

pkg/policy/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

pkg/policy/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"

pkg/policy/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"

pkg/policy/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"

pkg/policy/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

pkg/policy/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"

pkg/policy/testdata/policies/allow-canonical/doi/policy.rego

@@ -0,0 +1,11 @@
+package attest
+
+import rego.v1
+
+default canonical = false
+
+canonical if {
+  not input.tag
+}
+
+result := {"success": canonical}