feat: add attest sign/verify

internal/test/test.go

@@ -2,13 +2,22 @@ package test
 
 import (
 	"context"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
 	"os"
+	"strings"
 	"testing"
 
+	"github.com/docker/attest/pkg/attestation"
 	"github.com/docker/attest/pkg/oci"
 	"github.com/docker/attest/pkg/policy"
 	"github.com/docker/attest/pkg/signerverifier"
 	"github.com/docker/attest/pkg/tlog"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/layout"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
 	"github.com/secure-systems-lab/go-securesystemslib/dsse"
 )
 
@@ -84,3 +93,103 @@ func GetMockPolicy() policy.PolicyEvaluator {
 		},
 	}
 }
+
+type AnnotatedStatement struct {
+	OCIDescriptor   *v1.Descriptor
+	InTotoStatement *intoto.Statement
+	Annotations     map[string]string
+}
+
+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)
+	}
+	mfs2, err := mfs.IndexManifest()
+	if err != nil {
+		return nil, fmt.Errorf("failed to extract IndexManifest from ImageIndex: %w", err)
+	}
+
+	var statements []*AnnotatedStatement
+
+	for _, mf := range mfs2.Manifests {
+		if mf.Annotations["vnd.docker.reference.type"] != "attestation-manifest" {
+			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 := 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()
+			var intotoStatement = new(intoto.Statement)
+			var desc *v1.Descriptor
+			if strings.HasSuffix(string(mt), "+dsse") {
+				var env = new(attestation.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
+}

internal/test/test_test.go

@@ -0,0 +1,23 @@
+package test
+
+import (
+	"path/filepath"
+	"testing"
+
+	intoto "github.com/in-toto/in-toto-golang/in_toto"
+	"github.com/stretchr/testify/assert"
+)
+
+var (
+	UnsignedTestImage = filepath.Join("..", "..", "test", "testdata", "unsigned-test-image")
+)
+
+const (
+	ExpectedStatements = 4
+)
+
+func TestExtractAnnotatedStatements(t *testing.T) {
+	statements, err := ExtractAnnotatedStatements(UnsignedTestImage, intoto.PayloadType)
+	assert.NoError(t, err)
+	assert.Equalf(t, len(statements), ExpectedStatements, "expected %d statement, got %d", ExpectedStatements, len(statements))
+}