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fix: exclude correlation fields from the flex-auth request digest
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Verified the digest join against flex-auth's T03 replay fixtures and found
request_digest was hashing fields docs/canonical-request-digest.md excludes.
The material is tenant, subject, action, resource, context only: id is
correlation, policy_version lives in provenance, caring_context is hashed
separately. This engine included all three when present.

Because the join adopts the served request id, every real production request
would have carried one, so the computed digest would have matched no issued
decision and failed closed against every correct allow. Same unsatisfiable
shape as the removed AUTHORITY constant.

The old pinned constant was computed with the id inside the material, so it
was wrong and its passing proved nothing. Replaced with fixture-driven tests
over two real envelopes (vendored with provenance) plus a structural test
that correlation fields do not move the digest. Both fixtures are needed:
input_claim_digests.context appears only with a non-empty context.

Also stops computing the native claim digest. The claim's binding.action and
binding.target speak approval-engine's vocabulary while ours speaks the
catalog's, and no mapping is published; flex-auth makes no cross-check and
states the correspondence is ours via pdp_digest. A claim recording no
pdp_digest now fails closed naming the missing mapping rather than comparing
two different languages. That mapping is a prerequisite for destroy.

274 tests pass. Production still fails closed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01M65ovP3eiiPHubibvWs9mD

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 393550@bnt-lap001
Assistant-Session: 4bb359f9-1f12-4410-9e76-079cf23c82e4
This commit is contained in:
tegwick 2026-09-06 14:17:38 +02:00
parent 083bee7333
commit 6e9c15228c
11 changed files with 562 additions and 24 deletions
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20
src/secrets_engine/authorization.py
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@ -156,8 +156,26 @@ def canonical_check_request(request: object) -> dict[str, Any]:
return canonical
def request_digest(request: object) -> str:
#: Correlation-only or separately-hashed fields, excluded from the digest
#: material by docs/canonical-request-digest.md "What is hashed".
_UNHASHED_FIELDS = ("id", "policy_version", "caring_context")
def digest_material(request: object) -> dict[str, Any]:
"""The exact tuple flex-auth hashes: tenant, subject, action, resource, context.
``id`` is correlation only, ``policy_version`` is recorded in provenance, and
``caring_context`` is hashed separately as
``provenance.input_claim_digests.caring_context``. Including any of them
produces a digest that matches no real DecisionEnvelope, which fails closed
against every correctly issued decision.
"""
canonical = canonical_check_request(request)
return {k: v for k, v in canonical.items() if k not in _UNHASHED_FIELDS}
def request_digest(request: object) -> str:
canonical = digest_material(request)
encoded = json.dumps(
canonical, ensure_ascii=False, separators=(",", ":")
).encode("utf-8")