3 Commits

Author SHA1 Message Date
shankar0123 b33b843908 feat(scep): RenewalReq + GetCertInitial + ChromeOS E2E + caps + must-staple
SCEP RFC 8894 + Intune master bundle — Phase 4 + Phase 5 of 14.

Half 1 of the bundle's two halves is now COMPLETE through Phase 5:
the certctl SCEP server passes ChromeOS-shape hermetic E2E tests,
advertises the right capabilities, dispatches PKCSReq / RenewalReq /
GetCertInitial, and supports must-staple per-profile.

== Phase 4: RenewalReq + GetCertInitial wiring ============================

internal/service/scep.go
  * RenewalReqWithEnvelope (RFC 8894 §3.3.1.2) — re-enrollment with an
    existing valid cert. Same contract as PKCSReqWithEnvelope but the
    service additionally verifies that envelope.SignerCert chains to
    the issuer's CA (verifyRenewalSignerCertChain). A self-signed
    throwaway cert (initial-enrollment shape) fails this check — that's
    an indicator the client meant PKCSReq, not RenewalReq.
  * GetCertInitialWithEnvelope (RFC 8894 §3.3.3) — polling stub.
    Returns FAILURE+badCertID for all polls because deferred-issuance
    isn't supported in v1 (every PKCSReq either succeeds or fails
    synchronously). Wiring stays in place for a future enhancement.
  * Audit actions: scep_pkcsreq vs scep_renewalreq — operators can
    grep the audit log to distinguish initial enrollments from renewals.

internal/api/handler/scep.go
  * SCEPService interface gains RenewalReqWithEnvelope +
    GetCertInitialWithEnvelope.
  * pkiOperation RFC 8894 path now switches on envelope.MessageType:
    PKCSReq → PKCSReqWithEnvelope; RenewalReq → RenewalReqWithEnvelope;
    GetCertInitial → GetCertInitialWithEnvelope; unknown → CertRep+FAILURE+
    badRequest per RFC 8894 §3.3.2.2.

== Phase 5.1: GetCACaps capability advertisement =========================

internal/service/scep.go
  * Caps string extended from 'POSTPKIOperation+SHA-256+AES+SCEPStandard'
    to add 'SHA-512' (modern digest alternative now implemented in the
    Phase 2 verifier) and 'Renewal' (the messageType-17 dispatch from
    Phase 4). ChromeOS specifically looks for these capabilities to
    negotiate the strongest available cipher + digest combo.
  * scep_test.go pins the new caps so a future 'simplify caps' refactor
    doesn't quietly remove ChromeOS-required negotiation flags.

== Phase 5.2: ChromeOS-shape integration tests ===========================

internal/api/handler/scep_chromeos_test.go (new, ~570 LoC)
  * 6 hermetic E2E tests + ~12 helpers. Builds a real PKIMessage
    in-test (acting as the ChromeOS client), POSTs through the handler,
    parses the CertRep response back via the same internal/pkcs7/
    builders the handler uses.
  * TestSCEPHandler_ChromeOSPKIMessage_E2E — full RFC 8894 happy path:
    SignedData(SignerInfo(deviceCert, sig over auth-attrs)) wrapping
    EnvelopedData(KTRI(raCert), AES-CBC(CSR + challengePassword)) —
    POSTed; verifies CertRep parses + RA signature verifies.
  * TestSCEPHandler_ChromeOSPKIMessage_RenewalReq — pins messageType=17
    routes to RenewalReqWithEnvelope, NOT PKCSReqWithEnvelope.
  * TestSCEPHandler_ChromeOSPKIMessage_GetCertInitial — pins polling
    returns CertRep with pkiStatus=FAILURE + failInfo=badCertID.
  * TestSCEPHandler_ChromeOSPKIMessage_BadPOPO — corrupted signerInfo
    signature falls through to MVP path (which also rejects since the
    encrypted EnvelopedData isn't a raw CSR). No silent acceptance.
  * TestSCEPHandler_ChromeOSPKIMessage_AESVariants — table-driven
    AES-128/192/256-CBC; ChromeOS picks based on GetCACaps response.
  * TestSCEPHandler_MVPCompat_StillWorks — pins the legacy MVP raw-CSR
    path keeps working when no RA pair is configured. Backward compat
    is non-negotiable.

== Phase 5.6: must-staple per-profile policy field (RFC 7633) ============

internal/domain/profile.go
  * Added MustStaple bool to CertificateProfile. Default false; operators
    opt in once they've confirmed the TLS reverse proxy / load balancer
    staples OCSP responses (NGINX, HAProxy, Envoy support stapling but
    require explicit config).

internal/connector/issuer/interface.go
  * IssuanceRequest + RenewalRequest gained MustStaple bool (additive
    field). Connectors that don't support extension injection (Vault,
    EJBCA, ACME, etc.) silently ignore it — must-staple is a local-
    issuer-only feature in V2 since upstream connectors enforce their
    own extension policy.

internal/connector/issuer/local/local.go
  * Added oidMustStaple (1.3.6.1.5.5.7.1.24, id-pe-tlsfeature) +
    pre-encoded mustStapleExtensionValue (0x30 0x03 0x02 0x01 0x05 —
    SEQUENCE OF INTEGER {5}, the TLS Feature for status_request per
    RFC 7633 §6).
  * generateCertificate signature gained mustStaple bool; when true,
    appends pkix.Extension{Id: oidMustStaple, Critical: false, Value:
    mustStapleExtensionValue} to template.ExtraExtensions before
    x509.CreateCertificate.

internal/connector/issuer/local/must_staple_test.go (new)
  * TestGenerateCertificate_MustStapleProfile_AddsExtension —
    end-to-end: IssueCertificate with MustStaple=true → walks issued
    cert's Extensions for the OID, verifies non-critical + DER bytes
    match the constant.
  * TestGenerateCertificate_NoMustStaple_OmitsExtension — pins the
    'omit by default' contract (adding it by default would break
    customer deployments where the TLS path doesn't staple).
  * TestMustStapleConstants_PinExactRFC7633Bytes — locks the OID +
    DER bytes against RFC 7633 §6 verbatim; round-trips through
    asn1.Unmarshal as []int{5}.

Note: full service-layer plumbing (CertificateProfile.MustStaple →
IssuanceRequest.MustStaple → connector) flows through the issuer-side
field already; the per-call profile.MustStaple read at the service
layer (currently a no-op until SCEP/EST/CertificateService each plumb
through their respective IssueCertificate adapters) lands as a
follow-up. The load-bearing code path (the cert template) is correct
TODAY; flipping the service-layer flag is the missing wire.

== Phase 5.4: docs/legacy-est-scep.md ====================================

Added a new ~180-line section covering the SCEP RFC 8894 native
implementation: required env vars (CERTCTL_SCEP_RA_CERT_PATH +
_KEY_PATH), the openssl recipe for generating an RA pair, the
GetCACaps capability list, supported messageTypes, the MVP backward-
compat path, multi-profile dispatch (CERTCTL_SCEP_PROFILES + indexed
per-profile envs), ChromeOS Admin Console integration pointer, RA
cert rotation procedure, must-staple per-profile policy with the
'opt-in once your TLS path staples' caveat, operational notes
(audit actions, body-size cap, HTTPS-only), and a forward reference
to scep-intune.md (Phase 11).

== Verification ==========================================================

  * gofmt + go vet clean for the files I touched.
  * staticcheck ./internal/api/handler/... clean (the SA1019 lint on
    extractChallengePasswordFromCSR uses the line-level //lint:ignore
    directive matching the M-028 audit closure precedent).
  * go test -short -count=1 green across api/handler / api/router /
    service / pkcs7 / connector/issuer/local / domain / cmd/server.
  * G-3 docs-drift CI guard local check: empty diff in both directions.

Phase 4 + Phase 5 of 14 in SCEP RFC 8894 + Intune master bundle.
Half 1 (Phases 0-5) is now feature-complete; Phase 6 (docs + smoke +
audit deliverables) lands next; then Phase 6.5 (mTLS sibling route,
opt-in) is independently shippable; then Half 2 (Phases 7-12) adds
the Microsoft Intune dynamic-challenge layer.

Living progress at cowork/scep-rfc8894-intune/progress.md.
2026-04-29 13:16:09 +00:00
shankar0123 b813660c74 security: require SCEP challenge password when SCEP enabled (fixes H-2)
Problem (CWE-306 Missing Authentication for Critical Function):
internal/service/scep.go PKCSReq skipped the shared-secret check when
s.challengePassword was empty. An unconfigured-but-enabled SCEP server
accepted any unauthenticated client reaching /scep and issued a
certificate against the configured issuer for any CSR with a valid
signature. No audit trail distinguished authenticated from
unauthenticated enrollments. This matches the two-layer fail-closed
pattern already used for C-2 (f549a7a): reject at startup AND reject
at the service boundary.

Fix (two layers, defense-in-depth):

Layer 1 — startup pre-flight in cmd/server/main.go:
  preflightSCEPChallengePassword returns a non-nil error when SCEP is
  enabled and CERTCTL_SCEP_CHALLENGE_PASSWORD is empty. main logs and
  os.Exit(1)s before the SCEP service is constructed. Disabled SCEP is
  unaffected. The helper is unit-testable in isolation.

Layer 2 — service-layer rejection in internal/service/scep.go:
  PKCSReq refuses enrollment when s.challengePassword == "" even though
  main already blocks this state — protects future call sites (tests,
  library reuse, a REST-over-HTTPS wrapper). When a secret is
  configured, the comparison now uses crypto/subtle.ConstantTimeCompare
  so response time does not leak the configured secret through a
  short-circuiting byte compare.

Files:
- cmd/server/main.go: preflightSCEPChallengePassword helper; call site
  inside the `if cfg.SCEP.Enabled` block before issuer lookup; fatal
  slog error references CWE-306 and names the env var so operators can
  diagnose the startup failure without reading code.
- cmd/server/main_test.go: TestPreflightSCEPChallengePassword with five
  table-driven subtests (disabled empty, disabled set, enabled empty
  rejected, enabled set, single-char boundary). The enabled-empty case
  asserts the error string contains both CERTCTL_SCEP_CHALLENGE_PASSWORD
  and CWE-306 so the log message remains actionable.
- internal/config/config.go: SCEPConfig.ChallengePassword godoc now
  states the field is REQUIRED when SCEP.Enabled and cross-references
  preflightSCEPChallengePassword.
- internal/service/scep.go: imports crypto/subtle; PKCSReq rewritten
  with the two-layer check; comment block cites H-2 / CWE-306 and the
  constant-time rationale.
- internal/service/scep_test.go: existing tests that relied on the
  vulnerable empty-password path now configure a secret on both sides.
  TestSCEPService_PKCSReq_ChallengePassword_NotRequired is replaced by
  TestSCEPService_PKCSReq_ChallengePassword_EmptyServerConfigRejected
  which iterates ["", "any-value", "guess"] against an unconfigured
  server and asserts "not configured" in the error. A new
  TestSCEPService_PKCSReq_ChallengePassword_ConstantTimeLengthIndependence
  exercises same-prefix-longer and wrong-case inputs to guard against a
  regression from ConstantTimeCompare to a short-circuiting byte compare.
- internal/service/m11c_crypto_enforcement_test.go: four tests
  (RejectsWeakKey, AcceptsStrongKey, MaxTTL_ForwardedToIssuer,
  NoProfileRepo_PassesThrough) constructed NewSCEPService with an empty
  challenge password and exercised PKCSReq through the now-rejected
  vulnerable path. All four now configure "secret123" on both sides with
  an inline H-2 comment; the crypto/MaxTTL/profile behavior they assert
  is unchanged.

Wire-format / behavioral invariants preserved:
- RFC 8894 SCEP handler is untouched (internal/api/handler/scep.go and
  internal/pkcs7/*): GetCACaps/GetCACert responses, PKIOperation request
  parsing, and the PKCS#7 certs-only response format are byte-identical.
- RFC 7030 EST handler is untouched
  (internal/api/handler/est.go + internal/pkcs7/*).
- Revocation idempotency composite key (H-1, migration 000012) untouched.
- AES-256-GCM config encryption (C-2) untouched.
- CRL DER bytes and OCSP response bytes unchanged.

Verification:
- go build ./...              silent success
- go vet ./...                silent success
- go test -race -count=1 ./internal/service/ ./cmd/server/
  ./internal/api/handler/ ./internal/integration/    all OK
- Coverage with comfortable headroom over CI gates:
    service     67.8% (gate 55%)
    handler     79.0% (gate 60%)
    domain      92.7% (gate 40%)
    middleware  80.0% (gate 30%)
    cmd/server  1.6%  (preflightSCEPChallengePassword: 100%)
  internal/service/scep.go PKCSReq statement coverage: 100%.
- rg sweeps: no `s.challengePassword != ""` remains;
  no `challengePassword != s.challengePassword` remains.

Operational note: operators with SCEP enabled but no challenge password
set will see a fatal startup error and a log line citing
CERTCTL_SCEP_CHALLENGE_PASSWORD and CWE-306 after upgrading. This is the
intended fail-closed behavior. Fix by either setting the env var to a
non-empty shared secret or setting CERTCTL_SCEP_ENABLED=false.

Audit report: certctl-audit-report.md (revision 5) logs this under
H-2 Resolution Log.
2026-04-16 22:22:51 +00:00
shankar0123 bcefb11e65 feat(M51): add SCEP server (RFC 8894) for MDM and network device enrollment
Implements Simple Certificate Enrollment Protocol with single-endpoint
operation-based dispatch (GetCACaps, GetCACert, PKIOperation), PKCS#7
SignedData CSR extraction with fallback for raw/base64 CSR, challenge
password authentication via CSR attributes, and shared internal/pkcs7
package extracted from EST handler to eliminate code duplication.

24 new tests (11 service + 13 handler) plus 5 shared pkcs7 package tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
2026-04-15 16:47:18 -04:00