Files
certctl/internal/api/handler
shankar0123 e0d00717c7 feat(scep-intune): golden-file tests + e2e harness against fixture trust anchor
Phase 10 of the SCEP RFC 8894 + Intune master bundle. Adds reproducible
testdata fixtures + a hermetic end-to-end test that exercises the full
handler → service → dispatcher → CertRep wire path.

Phase 10.1 — Golden-file tests (internal/scep/intune/):

  * testdata/intune_trust_anchor.pem — deterministic ECDSA P-256 cert
    seeded from a constant byte string (sha256-derived PRNG); regenerates
    byte-identical PEM bytes across runs.
  * testdata/intune_challenge_golden_success.txt — valid challenge,
    iat/exp window covers goldenChallengeNow.
  * testdata/intune_challenge_golden_expired.txt — same trust anchor +
    payload shape but iat/exp shifted into the past.
  * testdata/intune_challenge_golden_tampered_sig.txt — payload bytes
    intact, last sig byte flipped.

  challenge_golden_test.go reads each fixture and asserts:
    - Success → ValidateChallenge returns a populated claim
      (DeviceName / Subject / SANDNS pinned to the documented values).
    - Expired → errors.Is(err, ErrChallengeExpired).
    - Tampered → errors.Is(err, ErrChallengeSignature).
    - Plus two defensive permutations: WrongAudienceReuse pins the
      audience-check ordering after a successful sig verify;
      RotatedTrustAnchorRejects pins the holder-rotation failure mode
      using a freshly-generated unrelated trust cert.

  golden_helper_test.go contains the deterministic-PRNG, ES256 signer,
  fixture-load helpers, and the regeneration target. Operators flip
  fixtures via:
    go test -run='^TestRegenerateGoldenFixtures$'             ./internal/scep/intune/... -args -update-golden

  Why ECDSA + a deterministic seed: a hand-pasted base64 blob would
  break on every Go stdlib bump (json.Marshal field ordering, ASN.1
  encoding edge cases). Generating from a pinned seed gives
  reproducible PEM bytes; only the ECDSA signature suffix varies
  across regenerations (Go's stdlib doesn't expose RFC 6979
  deterministic-k cleanly), and ValidateChallenge re-verifies the
  signature on every read so it doesn't matter.

  intune package coverage: 95.2% (was 94.8%).

Phase 10.2 — Hermetic end-to-end test (internal/api/handler/scep_intune_e2e_test.go):

  Departs from the spec's deploy/test/ location because the handler
  package already has the chromeOS-shape PKIMessage builders (buildTestCSR
  / buildEnvelopedDataForTest / buildSignedDataForTest / aesCBCEncrypt /
  postPKIOperation). Putting the e2e test in the handler package lets it
  reuse those helpers AND run in the default 'go test ./...' sweep —
  every CI run exercises the full Intune dispatcher chain. The
  deploy/test/ location is reserved for a future docker-compose-driven
  variant that would mount a fixture trust anchor into the running
  container; this hermetic version proves the wire works without that
  dependency.

  intuneE2EFixture stands up:
    - A real Intune Connector signing keypair (ECDSA P-256) + cert
      written to a temp PEM file the TrustAnchorHolder loads at startup.
    - A real RA pair the SCEPHandler decrypts EnvelopedData with.
    - A fixture issuer connector (intuneE2EIssuerConnector) that
      records every IssueCertificate call + returns a deterministic
      child cert chained to a fixture CA. Implements the full
      IssuerConnector interface (IssueCertificate / RenewCertificate /
      RevokeCertificate / GenerateCRL / SignOCSPResponse / GetRenewalInfo)
      with the non-issuance methods stubbed.
    - A capturing AuditRepository that records every Create call so
      the test can assert action='scep_pkcsreq_intune' was emitted.
    - A real SCEPService with SetIntuneIntegration wired to a real
      ReplayCache + PerDeviceRateLimiter.

  Three test scenarios:

    1. TestSCEPIntuneEnrollment_E2E — the documented happy path. Forge
       a valid Intune-shaped challenge (ES256 signed, length > 200, two
       dots — satisfies looksIntuneShaped), build a CSR with CN matching
       the claim's device_name, POST through HandleSCEP, decode the
       CertRep, assert pkiStatus=SUCCESS + issuer.issued has one entry
       + audit log carries 'scep_pkcsreq_intune' + IntuneStats.counters[
       'success']==1.

    2. TestSCEPIntuneEnrollment_ClaimMismatchRejected_E2E — same setup
       but CSR CN is 'attacker-host.example.com'. Dispatcher must
       reject with CertRep FAILURE+BadRequest (mapIntuneErrorToFailInfo:
       ErrClaimCNMismatch → BadRequest), no issuance, IntuneStats
       counters['claim_mismatch']==1.

    3. TestSCEPIntuneEnrollment_TamperedSignature_E2E — flip a byte in
       the JWT signature segment of the Intune challenge before
       wrapping it in the PKIMessage. Dispatcher rejects with
       FAILURE+BadMessageCheck (signature errors → BadMessageCheck per
       the same mapping table).

  Important sanity learning during construction: the buildTestCSR
  helper from scep_chromeos_test.go does NOT populate DNSNames on the
  CSR. The success claim therefore omits san_dns to avoid tripping
  ErrClaimSANDNSMismatch (claim says ['x'], CSR has nothing). The
  claim_mismatch sibling test exercises the SAN-dimension via the
  CN mismatch path; coverage of explicit SANDNS mismatches stays in
  the unit tests in claim_test.go where the helper builds CSRs with
  full SANs.

Verification:
  * gofmt clean on touched files
  * go vet ./internal/scep/intune/... ./internal/api/handler/...: clean
  * staticcheck: clean
  * go test -count=1 -cover ./internal/scep/intune/...: 95.2%
  * 5 golden tests + 3 e2e tests all pass
  * No new env vars (G-3 docs guard not triggered)
  * No new HTTP routes (openapi-parity guard not triggered)
  * Sibling test packages (service + router) still green

Refs: cowork/scep-rfc8894-intune-master-prompt.md::Phase 10
      cowork/scep-rfc8894-intune/progress.md
2026-04-29 16:55:52 +00:00
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