 Jon Chery
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ab069db3a4
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feat(P02): JWS-from-PAT key derivation via HKDF-SHA256 (REQ-332, C-5.2, security-engineer)
---ci---
project: acdl
phase: 2
milestone: v1.28
status: execute
persona: security-engineer
---
C-5.2 grill fix: symmetric JWS (HS256) where the PAT is the shared secret.
derive_signing_key(pat) -> HKDF-SHA256(pat.encode(), salt=b'nova-local-
attestation', info=b'jws-signing-key', length=32) via cryptography (fallback
to hashlib HKDF). sign_attestation(payload, pat) -> compact JWS
b64url(header).b64url(payload).b64url(sig) with header {alg:HS256,typ:JWT}.
verify_attestation(jws, pat) -> payload (raises JWSValidationError on tamper
or wrong PAT; hmac.compare_digest constant-time). INV-14..17 enforced
(key derived from PAT, not cached, fixed salt/info, constant-time compare).
tests/test_jws_attestation.py: 20 tests (round-trip, tamper, wrong-PAT,
invariants, hashlib/crypto parity).
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2026-08-19 22:48:21 +00:00 |
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