Security: fail-closed expiry verification + constant-time key compare#21
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…jwt_token A present-but-unparseable expires_at (naive timestamp, malformed string, or non-string value) previously hit an 'except (ValueError, TypeError): pass' and fell through to status='valid' -- a silent fail-open that let a corrupted, naive, or tampered expiry bypass expiry entirely in a security library. - Add _parse_expiry(): returns an aware UTC datetime, normalizing naive values to UTC so comparisons never raise; returns None only when truly unparseable. - verify_api_key/verify_jwt_token now fail CLOSED: a set-but-unparseable expires_at yields status='invalid' instead of 'valid'. - Harden the key-hash match with hmac.compare_digest (constant-time) and skip entries whose stored hash is missing/non-string. - +7 regression tests (tests/test_verify_expiry_failclosed.py) covering naive past/future, malformed, and non-string expiries for keys and JWTs. check_expiry (display helper) behavior is unchanged (tests lock in None-on- unparseable). 76 tests pass; changed files ruff-clean.
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| continue | ||
| if entry.get("key_hash") == key_hash: | ||
| stored_hash = entry.get("key_hash") | ||
| if isinstance(stored_hash, str) and hmac.compare_digest(stored_hash, key_hash): |
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Guard non-ASCII stored hashes before comparison
When any API-key entry has a malformed non-ASCII string in key_hash (for example, a migrated or corrupted record containing "é"), hmac.compare_digest raises TypeError for non-ASCII str inputs. Since this loop scans every API-key record, such an earlier entry prevents verification of all subsequent otherwise-valid keys instead of simply treating the malformed hash as non-matching, which was the prior behavior.
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Council Gate Verdict — APPROVERisk level: high (auth/security — fail-closed expiry + constant-time key compare)
Summary: All four council members voted Action: Applying label |
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Council Merge Gate — clean APPROVE this cycle, still policy-BLOCKED. |
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Council Merge Gate — clean APPROVE (session |
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Council Merge Gate — clean APPROVE this cycle, still policy-BLOCKED. |
Council Merge Gate — clean APPROVE, still policy-BLOCKED
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Council Merge Gate — clean APPROVE, still policy-BLOCKED
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Council Merge Gate — clean APPROVE, still policy-BLOCKED
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🔎 Pre-PR Code Review —
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Council Merge Gate — clean APPROVE, still policy-BLOCKED
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
Council Merge Gate - REWORKThe model-council merge gate returned REWORK for this PR. Per repo policy, the PR is left open for rework. Council session: Council merge gate: REWORK. Merge allowed. Posted automatically by the |
Council Merge Gate - REWORKThe model-council merge gate returned REWORK for this PR. Per repo policy, the PR is left open for rework. Council session: Council merge gate: REWORK. Merge allowed. Posted automatically by the |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
13 similar comments
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
7 similar comments
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
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Council Merge Gate -- REWORK This PR was submitted to the model-council merge gate after the council-review approval. The merge gate returned REWORK (not a clean APPROVE), so it was left open and not merged. Please address the council's concerns and re-run the review gate before merge. (This is an automated notice; no human was overridden.) |
Council Merge Gate - REWORKThe model-council merge gate returned REWORK for this PR. Per repo policy, the PR is left open for rework. Council session: Council merge gate: REWORK. Merge allowed. Posted automatically by the |
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Automated council merge gate ran for this PR. The gate returned Note: the underlying gate response also marked |
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Pre-PR Code Review — Verdict: APPEAR-SAFE (posted as COMMENT per self-review embargo)
Diff: +123/-15, security hardening
Changes two verification functions in keygen.py:
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Constant-time key comparison — Replaces
stored_hash == key_hashwithhmac.compare_digest(stored_hash, key_hash)to prevent timing side-channel attacks on API key verification. -
Fail-closed expiry parsing — Replaces the old
try/except: passpattern (which silently accepted any unparseable expiry timestamp as "valid") with a dedicated_parse_expiry()helper that returnsNoneon failure, causing the caller to returnstatus="invalid"instead. Bothverify_api_keyandverify_jwt_tokenare fixed. -
Regression tests (85 lines, 2 test classes, 7 test methods) covering naive past/future timestamps, malformed expiry strings, non-string expiry values, and valid Zulu timestamps.
Assessment
- ✅ Correct, well-tested. The
_parse_expiryfunction handles naive datetimes (assumed UTC), Zulu-suffix, malformed strings, and non-string values. The tests lock in the expected fail-closed behavior. - ✅ CI green: test matrix (3.10–3.13), security, build, code-review all ✅. The
ensure-prfailure is pre-existing. - ✅ No prior-fix regression — Engraphis recall shows no previous review findings for this code area.
⚠️ Small concern:_parse_expiryis defined afterrotate_keybut beforeverify_api_key— worth noting for readability but not a logic issue.
Verdict
Appear-safe with one minor suggestion. The code is sound, the fix eliminates a real security fail-open class, and tests are thorough. I would suggest moving _parse_expiry before verify_api_key (not after rotate_key) for natural reading order, but this is non-blocking.
Formal APPROVE withheld per fleet self-approval embargo (single cowork-bot author, <3 distinct reviewers, PR age 32h ✅). Meets merge-readiness otherwise.
Council Merge Gate - REWORKThe model-council merge gate returned REWORK for this PR. Per repo policy, the PR is left open for rework. Council session: Council merge gate: REWORK. Merge allowed. Posted automatically by the |
Summary
Hardens
src/apiauth/keygen.pyverification paths in the auth library:expires_atnow returnsstatus="invalid"instead of silently falling through to"valid"(previously anexcept: passswallowedTypeError/ValueErrorand reported expired/corrupted keys as valid — a silent fail-open in a security library).hmac.compare_digestinstead of==, removing a timing side-channel on key verification._parse_expiry()normalizes naive timestamps to UTC-aware datetimes so comparisons never raise.Test plan
tests/test_verify_expiry_failclosed.pylocking in fail-closed behavior for naive/unparseable expiries.76 passed.Notes
master) is not pushed by this job.🤖 Generated with Claude Code