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Verifier: Use correct Timestamp hash algorithm #1385

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Verifier: Use correct Timestamp hash algorithm #1385

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0da31a1
Verifier: Use correct algorithm for Timestamp hash
jku May 15, 2025
f8ea3da
verify: Add temporary mypy ignore
jku May 21, 2025
3eb2be6
Merge branch 'main' into use-correct-hash-algo
jku May 21, 2025
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4 changes: 4 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,10 @@ All versions prior to 0.9.0 are untracked.
* TSA: Changed the Timestamp Authority requests to explicitly use sha256 for message digests.
[#1373](https://github.com/sigstore/sigstore-python/pull/1373)

* TSA: Correctly verify timestamps with hashes other than SHA-256. Currently supported
algorithms are SHA-256, SHA-384, SHA-512.
[#1373](https://github.com/sigstore/sigstore-python/pull/1373)

* Fixed the certificate calidity period check for Timestamp Authorities (TSA).
Certificates need not have and end date, while still requiring a start date.
[#1368](https://github.com/sigstore/sigstore-python/pull/1368)
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2 changes: 1 addition & 1 deletion pyproject.toml
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Expand Up @@ -36,7 +36,7 @@ dependencies = [
"requests",
"rich >= 13,< 15",
"rfc8785 ~= 0.1.2",
"rfc3161-client >= 0.1.2,< 1.1.0",
"rfc3161-client >= 1.0.2,< 1.1.0",
# NOTE(ww): Both under active development, so strictly pinned.
"sigstore-protobuf-specs == 0.4.2",
"sigstore-rekor-types == 0.0.18",
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14 changes: 5 additions & 9 deletions sigstore/verify/verifier.py
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Expand Up @@ -125,7 +125,7 @@ def _from_trust_config(cls, trust_config: ClientTrustConfig) -> Verifier:
)

def _verify_signed_timestamp(
self, timestamp_response: TimeStampResponse, signature: bytes
self, timestamp_response: TimeStampResponse, message: bytes
) -> TimestampVerificationResult | None:
"""
Verify a Signed Timestamp using the TSA provided by the Trusted Root.
Expand All @@ -140,7 +140,8 @@ def _verify_signed_timestamp(

verifier = builder.build()
try:
verifier.verify(timestamp_response, signature)
# TODO: remove ignore after rfc3161-client upgrade
verifier.verify_message(timestamp_response, message) # type: ignore[attr-defined]
except Rfc3161VerificationError as e:
_logger.debug("Unable to verify Timestamp with CA.")
_logger.exception(e)
Expand Down Expand Up @@ -183,15 +184,10 @@ def _verify_timestamp_authority(
msg = "duplicate timestamp found"
raise VerificationError(msg)

# The Signer sends a hash of the signature as the messageImprint in a TimeStampReq
# to the Timestamping Service
signature_hash = sha256_digest(bundle.signature).digest
verified_timestamps = [
verified_timestamp
result
for tsr in timestamp_responses
if (
verified_timestamp := self._verify_signed_timestamp(tsr, signature_hash)
)
if (result := self._verify_signed_timestamp(tsr, bundle.signature))
]

return verified_timestamps
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