Fix double encoding. Remove annotations

pkg/attest/sign_test.go

@@ -223,7 +223,7 @@ func TestSimpleStatementSigning(t *testing.T) {
 				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, "e30=", string(mf.Config.Data))
+				assert.Equal(t, "{}", string(mf.Config.Data))
 				layers, err := img.Layers()
 				require.NoError(t, err)
 				assert.Len(t, layers, 1)

pkg/attest/verify.go

@@ -166,11 +166,6 @@ func VerifyAttestations(ctx context.Context, resolver oci.AttestationResolver, p
 }
 
 func NewAttestationManifest(subject *v1.Descriptor) (*attestation.AttestationManifest, error) {
-	subjectDigest := subject.Digest.String()
-	subject.Annotations = map[string]string{
-		"vnd.docker.reference.digest": subjectDigest,
-		"vnd.docker.reference.type":   "attestation-manifest"}
-
 	return &attestation.AttestationManifest{
 		OriginalDescriptor: &v1.Descriptor{
 			MediaType: "application/vnd.oci.image.manifest.v1+json",

pkg/attestation/attestation.go

@@ -303,7 +303,7 @@ func (i *EmptyConfigImage) Manifest() (*v1.Manifest, error) {
 		MediaType: "application/vnd.oci.empty.v1+json",
 		Size:      2,
 		Digest:    v1.Hash{Algorithm: "sha256", Hex: "44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a"},
-		Data:      []byte("e30="),
+		Data:      []byte("{}"),
 	}
 	return mf, nil
 }