Support timestamps in the attestation

Author: jku

src/pypi_attestations/_cli.py

@@ -428,9 +428,6 @@ def _sign(args: argparse.Namespace) -> None:
         _die(f"Failed to detect identity: {identity_error}")
 
     trust_config = ClientTrustConfig.staging() if args.staging else ClientTrustConfig.production()
-    # Make sure we use rekor v1 until attestations are compatible with v2
-    trust_config.force_tlog_version = 1
-
     signing_ctx = SigningContext.from_trust_config(trust_config)
 
     # Validates that every file we want to sign exist but none of their attestations

src/pypi_attestations/_impl.py

@@ -24,6 +24,7 @@
 from pydantic import Base64Bytes, BaseModel, ConfigDict, Field, field_validator
 from pydantic.alias_generators import to_snake
 from pydantic_core import ValidationError
+from rfc3161_client import decode_timestamp_response
 from sigstore._utils import _sha256_streaming
 from sigstore.dsse import DigestSet, StatementBuilder, Subject, _Statement
 from sigstore.dsse import Envelope as DsseEnvelope
@@ -136,6 +137,7 @@ def __init__(self: VerificationError, msg: str) -> None:
 
 
 TransparencyLogEntry = NewType("TransparencyLogEntry", dict[str, Any])
+Timestamp = NewType("Timestamp", bytes)
 
 
 class VerificationMaterial(BaseModel):
@@ -152,6 +154,11 @@ class VerificationMaterial(BaseModel):
     and certificate.
     """
 
+    timestamps: list[Timestamp] = []
+    """
+    list of RFC3161 timestamps. List may be empty if all transparency entries are rekor v1.
+    """
+
 
 class Attestation(BaseModel):
     """Attestation object as defined in PEP 740."""
@@ -347,10 +354,16 @@ def to_bundle(self) -> Bundle:
         except (ValidationError, sigstore.errors.Error) as err:
             raise ConversionError("invalid transparency log entry") from err
 
+        timestamps = [
+            decode_timestamp_response(base64.b64encode(t))
+            for t in self.verification_material.timestamps
+        ]
+
         return Bundle._from_parts(  # noqa: SLF001
             cert=certificate,
             content=evp,
             log_entry=log_entry,
+            signed_timestamp=timestamps,
         )
 
     @classmethod
@@ -368,13 +381,19 @@ def from_bundle(cls, sigstore_bundle: Bundle) -> Attestation:
         if len(envelope.signatures) != 1:
             raise ConversionError(f"expected exactly one signature, got {len(envelope.signatures)}")
 
+        timestamps = []
+        if sigstore_bundle.verification_material.timestamp_verification_data:
+            ts_data = sigstore_bundle.verification_material.timestamp_verification_data
+            timestamps = [base64.b64encode(ts.as_bytes()) for ts in ts_data.rfc3161_timestamps]
+
         return cls(
             version=1,
             verification_material=VerificationMaterial(
                 certificate=base64.b64encode(certificate),
                 transparency_entries=[
                     sigstore_bundle.log_entry._inner.to_dict()  # noqa: SLF001
                 ],
+                timestamps=timestamps,
             ),
             envelope=Envelope(
                 statement=base64.b64encode(envelope.payload),

test/test_impl.py

@@ -70,8 +70,6 @@ class TestAttestation:
     @online
     def test_roundtrip(self, id_token: IdentityToken) -> None:
         trust_config = ClientTrustConfig.staging()
-        # Make sure we use rekor v1 until attestations are compatible with v2
-        trust_config.force_tlog_version = 1
         sign_ctx = SigningContext.from_trust_config(trust_config)
 
         with sign_ctx.signer(id_token) as signer:
@@ -107,8 +105,6 @@ def in_validity_period(_: IdentityToken) -> bool:
         monkeypatch.setattr(IdentityToken, "in_validity_period", in_validity_period)
 
         trust_config = ClientTrustConfig.staging()
-        # Make sure we use rekor v1 until attestations are compatible with v2
-        trust_config.force_tlog_version = 1
         sign_ctx = SigningContext.from_trust_config(trust_config)
 
         with sign_ctx.signer(id_token, cache=False) as signer:
@@ -128,8 +124,6 @@ def get_bundle(*_: Any) -> Bundle:
         monkeypatch.setattr(sigstore.sign.Signer, "sign_dsse", get_bundle)
 
         trust_config = ClientTrustConfig.staging()
-        # Make sure we use rekor v1 until attestations are compatible with v2
-        trust_config.force_tlog_version = 1
         sign_ctx = SigningContext.from_trust_config(trust_config)
 
         with pytest.raises(impl.AttestationError):