Include URI for CA verified timestamps (#270)

Include the URI of the transparency log and timestamp authority for
verified timestamps in the final verification result. The URIs are
helpful for human readability of the result.

When the WithoutAnyObserverTimestampsUnsafe verify policy is selected,
there is no certificate authority, so the URI is left empty.

Signed-off-by: Colleen Murphy <colleenmurphy@google.com>

pkg/root/trusted_root.go

@@ -279,7 +279,9 @@ func ParseCertificateAuthority(certAuthority *prototrustroot.CertificateAuthorit
  }
  }
 
- // TODO: Should we inspect/enforce ca.Subject and ca.Uri?
+ certificateAuthority.URI = certAuthority.Uri
+
+ // TODO: Should we inspect/enforce ca.Subject?
  // TODO: Handle validity period (ca.ValidFor)
 
  return certificateAuthority, nil

pkg/verify/signed_entity.go

@@ -667,7 +667,7 @@ func (v *SignedEntityVerifier) VerifyTransparencyLogInclusion(entity SignedEntit
  }
 
  for _, vts := range verifiedTlogTimestamps {
- verifiedTimestamps = append(verifiedTimestamps, TimestampVerificationResult{Type: "Tlog", URI: "TODO", Timestamp: vts})
+ verifiedTimestamps = append(verifiedTimestamps, TimestampVerificationResult{Type: "Tlog", URI: vts.URI, Timestamp: vts.Time})
  }
  }
 
@@ -692,7 +692,7 @@ func (v *SignedEntityVerifier) VerifyObserverTimestamps(entity SignedEntity, log
  return nil, err
  }
  for _, vts := range verifiedSignedTimestamps {
- verifiedTimestamps = append(verifiedTimestamps, TimestampVerificationResult{Type: "TimestampAuthority", URI: "TODO", Timestamp: vts})
+ verifiedTimestamps = append(verifiedTimestamps, TimestampVerificationResult{Type: "TimestampAuthority", URI: vts.URI, Timestamp: vts.Time})
  }
  }
 
@@ -719,7 +719,7 @@ func (v *SignedEntityVerifier) VerifyObserverTimestamps(entity SignedEntity, log
  // append all timestamps
  verifiedTimestamps = append(verifiedTimestamps, logTimestamps...)
  for _, vts := range verifiedSignedTimestamps {
- verifiedTimestamps = append(verifiedTimestamps, TimestampVerificationResult{Type: "TimestampAuthority", URI: "TODO", Timestamp: vts})
+ verifiedTimestamps = append(verifiedTimestamps, TimestampVerificationResult{Type: "TimestampAuthority", URI: vts.URI, Timestamp: vts.Time})
  }
  }
 

pkg/verify/signed_entity_test.go

@@ -94,6 +94,7 @@ func TestEntitySignedByPublicGoodWithTlogVerifiesSuccessfully(t *testing.T) {
  assert.NotNil(t, res.Signature.Certificate)
  assert.Equal(t, "https://github.com/sigstore/sigstore-js/.github/workflows/release.yml@refs/heads/main", res.Signature.Certificate.SubjectAlternativeName)
  assert.NotEmpty(t, res.VerifiedTimestamps)
+ assert.Equal(t, "https://rekor.sigstore.dev", res.VerifiedTimestamps[0].URI)
 
  // verifies with integrated timestamp threshold too
  v, err = verify.NewSignedEntityVerifier(tr, verify.WithTransparencyLog(1), verify.WithIntegratedTimestamps(1))

pkg/verify/tlog.go

@@ -21,7 +21,6 @@ import (
  "encoding/hex"
  "errors"
  "fmt"
- "time"
 
  rekorClient "github.com/sigstore/rekor/pkg/client"
  rekorGeneratedClient "github.com/sigstore/rekor/pkg/generated/client"
@@ -43,7 +42,7 @@ const maxAllowedTlogEntries = 32
 // that must be verified.
 //
 // If online is true, the log entry is verified against the Rekor server.
-func VerifyArtifactTransparencyLog(entity SignedEntity, trustedMaterial root.TrustedMaterial, logThreshold int, trustIntegratedTime, online bool) ([]time.Time, error) { //nolint:revive
+func VerifyArtifactTransparencyLog(entity SignedEntity, trustedMaterial root.TrustedMaterial, logThreshold int, trustIntegratedTime, online bool) ([]Timestamp, error) { //nolint:revive
  entries, err := entity.TlogEntries()
  if err != nil {
  return nil, err
@@ -75,7 +74,7 @@ func VerifyArtifactTransparencyLog(entity SignedEntity, trustedMaterial root.Tru
  return nil, err
  }
 
- verifiedTimestamps := []time.Time{}
+ verifiedTimestamps := []Timestamp{}
  logEntriesVerified := 0
 
  for _, entry := range entries {
@@ -84,29 +83,29 @@ func VerifyArtifactTransparencyLog(entity SignedEntity, trustedMaterial root.Tru
  return nil, err
  }
 
+ rekorLogs := trustedMaterial.RekorLogs()
+ keyID := entry.LogKeyID()
+ hex64Key := hex.EncodeToString([]byte(keyID))
+ tlogVerifier, ok := trustedMaterial.RekorLogs()[hex64Key]
+ if !ok {
+ // skip entries the trust root cannot verify
+ continue
+ }
  if !online {
  if !entry.HasInclusionPromise() && !entry.HasInclusionProof() {
  return nil, fmt.Errorf("entry must contain an inclusion proof and/or promise")
  }
  if entry.HasInclusionPromise() {
- err = tlog.VerifySET(entry, trustedMaterial.RekorLogs())
+ err = tlog.VerifySET(entry, rekorLogs)
  if err != nil {
  // skip entries the trust root cannot verify
  continue
  }
  if trustIntegratedTime {
- verifiedTimestamps = append(verifiedTimestamps, entry.IntegratedTime())
+ verifiedTimestamps = append(verifiedTimestamps, Timestamp{Time: entry.IntegratedTime(), URI: tlogVerifier.BaseURL})
  }
  }
  if entity.HasInclusionProof() {
- keyID := entry.LogKeyID()
- hex64Key := hex.EncodeToString([]byte(keyID))
- tlogVerifier, ok := trustedMaterial.RekorLogs()[hex64Key]
- if !ok {
- // skip entries the trust root cannot verify
- continue
- }
-
  verifier, err := getVerifier(tlogVerifier.PublicKey, tlogVerifier.SignatureHashFunc)
  if err != nil {
  return nil, err
@@ -119,14 +118,6 @@ func VerifyArtifactTransparencyLog(entity SignedEntity, trustedMaterial root.Tru
  // DO NOT use timestamp with only an inclusion proof, because it is not signed metadata
  }
  } else {
- keyID := entry.LogKeyID()
- hex64Key := hex.EncodeToString([]byte(keyID))
- tlogVerifier, ok := trustedMaterial.RekorLogs()[hex64Key]
- if !ok {
- // skip entries the trust root cannot verify
- continue
- }
-
  client, err := getRekorClient(tlogVerifier.BaseURL)
  if err != nil {
  return nil, err
@@ -160,7 +151,7 @@ func VerifyArtifactTransparencyLog(entity SignedEntity, trustedMaterial root.Tru
  }
  }
  if trustIntegratedTime {
- verifiedTimestamps = append(verifiedTimestamps, entry.IntegratedTime())
+ verifiedTimestamps = append(verifiedTimestamps, Timestamp{Time: entry.IntegratedTime(), URI: tlogVerifier.BaseURL})
  }
  }
  // Ensure entry signature matches signature from bundle

pkg/verify/tlog_test.go

@@ -35,7 +35,7 @@ func TestTlogVerifier(t *testing.T) {
  entity, err := virtualSigstore.Attest("foo@example.com", "issuer", statement)
  assert.NoError(t, err)
 
- var ts []time.Time
+ var ts []verify.Timestamp
  ts, err = verify.VerifyArtifactTransparencyLog(entity, virtualSigstore, 1, true, false)
  assert.NoError(t, err)
  // 1 verified timestamp

pkg/verify/tsa.go

@@ -28,9 +28,14 @@ import (
 
 const maxAllowedTimestamps = 32
 
+type Timestamp struct {
+ Time time.Time
+ URI string
+}
+
 // VerifyTimestampAuthority verifies that the given entity has been timestamped
 // by a trusted timestamp authority and that the timestamp is valid.
-func VerifyTimestampAuthority(entity SignedEntity, trustedMaterial root.TrustedMaterial) ([]time.Time, error) { //nolint:revive
+func VerifyTimestampAuthority(entity SignedEntity, trustedMaterial root.TrustedMaterial) ([]Timestamp, error) { //nolint:revive
  signedTimestamps, err := entity.Timestamps()
  if err != nil {
  return nil, err
@@ -62,7 +67,7 @@ func VerifyTimestampAuthority(entity SignedEntity, trustedMaterial root.TrustedM
  return nil, err
  }
 
- verifiedTimestamps := []time.Time{}
+ verifiedTimestamps := []Timestamp{}
  for _, timestamp := range signedTimestamps {
  verifiedSignedTimestamp, err := verifySignedTimestamp(timestamp, signatureBytes, trustedMaterial, verificationContent)
 
@@ -82,7 +87,7 @@ func VerifyTimestampAuthority(entity SignedEntity, trustedMaterial root.TrustedM
 //
 // The threshold parameter is the number of unique timestamps that must be
 // verified.
-func VerifyTimestampAuthorityWithThreshold(entity SignedEntity, trustedMaterial root.TrustedMaterial, threshold int) ([]time.Time, error) { //nolint:revive
+func VerifyTimestampAuthorityWithThreshold(entity SignedEntity, trustedMaterial root.TrustedMaterial, threshold int) ([]Timestamp, error) { //nolint:revive
  verifiedTimestamps, err := VerifyTimestampAuthority(entity, trustedMaterial)
  if err != nil {
  return nil, err
@@ -93,7 +98,7 @@ func VerifyTimestampAuthorityWithThreshold(entity SignedEntity, trustedMaterial
  return verifiedTimestamps, nil
 }
 
-func verifySignedTimestamp(signedTimestamp []byte, dsseSignatureBytes []byte, trustedMaterial root.TrustedMaterial, verificationContent VerificationContent) (time.Time, error) {
+func verifySignedTimestamp(signedTimestamp []byte, dsseSignatureBytes []byte, trustedMaterial root.TrustedMaterial, verificationContent VerificationContent) (Timestamp, error) {
  certAuthorities := trustedMaterial.TimestampingAuthorities()
 
  // Iterate through TSA certificate authorities to find one that verifies
@@ -124,8 +129,8 @@ func verifySignedTimestamp(signedTimestamp []byte, dsseSignatureBytes []byte, tr
  }
 
  // All above verification successful, so return nil
- return timestamp.Time, nil
+ return Timestamp{Time: timestamp.Time, URI: ca.URI}, nil
  }
 
- return time.Time{}, errors.New("unable to verify signed timestamps")
+ return Timestamp{}, errors.New("unable to verify signed timestamps")
 }

pkg/verify/tsa_test.go

@@ -60,7 +60,7 @@ func TestTimestampAuthorityVerifierWithoutThreshold(t *testing.T) {
  virtualSigstore2, err := ca.NewVirtualSigstore()
  assert.NoError(t, err)
 
- var ts []time.Time
+ var ts []verify.Timestamp
 
  // expect one verified timestamp
  ts, err = verify.VerifyTimestampAuthority(entity, virtualSigstore)