M-001/M-006: strip HTTP auth from EST/SCEP + fail-loud SCEP preflight

Closes CWE-306 (missing authentication for critical function) for SCEP
via a fail-loud startup gate, and aligns EST/SCEP HTTP dispatch with
their respective RFCs. CRL/OCSP remain unauthenticated under
.well-known/pki/* per RFC 5280 §5 / RFC 6960 / RFC 8615. Option (D):
no mTLS in this milestone.

- RFC 7030 §3.2.3 (EST auth is deployment-specific) and §4.1.1
  (/cacerts explicitly anonymous): EST paths served unauthenticated;
  CSR-signature + profile policy enforce identity inside ESTService.
- RFC 8894 §3.2: SCEP authenticates via the challengePassword
  PKCS#10 attribute (OID 1.2.840.113549.1.9.7), not an HTTP credential.
  HTTP dispatch is unauthenticated; preflightSCEPChallengePassword
  refuses to start when CERTCTL_SCEP_ENABLED=true without
  CERTCTL_SCEP_CHALLENGE_PASSWORD. SCEPService.PKCSReq enforces the
  same invariant defense-in-depth and compares with
  crypto/subtle.ConstantTimeCompare.

cmd/server/main.go:
- Extract buildFinalHandler(apiHandler, noAuthHandler, webDir,
  dashboardEnabled); route /.well-known/est/*, /scep, /scep/*,
  /.well-known/pki/crl/{id}, /.well-known/pki/ocsp/{id}/{serial},
  and health probes through noAuthHandler (RequestID +
  structuredLogger + Recovery only).
- Add preflightSCEPChallengePassword fail-loud gate; startup log
  emits challenge_password_set boolean for operator visibility.

cmd/server/finalhandler_test.go (new, 314 lines, 27 subtests):
- TestBuildFinalHandler_Dispatch (20) + TestBuildFinalHandler_NoDashboard
  (7) pin the dispatch surface: EST 4-endpoint, SCEP exact +
  trailing-slash + query-string, PKI CRL+OCSP, health, /api/v1/*
  authenticated, /assets/* file server, SPA fallback.

internal/api/router/router.go, internal/config/config.go:
- Router-level comments explain why EST/SCEP/PKI dispatchers sit
  outside the authenticated mux; SCEP challenge password config
  plumbed through.

docs/architecture.md:
- New EST Authentication subsection (RFC 7030 §3.2.3 + §4.1.1,
  buildFinalHandler + noAuthHandler references).
- Rewrite SCEP Authentication subsection; replaces pre-existing
  factually-incorrect "any value accepted" claim with CWE-306
  preflight, service-layer defense-in-depth, and
  crypto/subtle.ConstantTimeCompare.
- Top-level Authentication section: qualify /api/v1/* scope on API
  clients bullet; add standards-based-endpoints bullet referencing
  the 27-subtest regression harness.

docs/compliance-soc2.md:
- CC6.1: scope API Key Authentication to /api/v1/*; add
  standards-based endpoints bullet citing RFCs and CWE-306 closure.
- CC6.3: scope API Key Policy to /api/v1/* with cross-reference to
  CC6.1.
- Evidence Locations augmented with buildFinalHandler,
  preflightSCEPChallengePassword, scep.go defense path, regression
  harness, and OpenAPI security:[] overrides.

api/openapi.yaml: verified already correct (global bearerAuth
default overridden with security:[] on /cacerts, /simpleenroll,
/simplereenroll, /csrattrs, /scep GET+POST, /crl/{issuer_id},
/ocsp/{issuer_id}/{serial}); no edits needed.

docs/architecture.md

@@ -723,6 +723,8 @@ type ESTService interface {
 
 **Issuer connector extension:** EST required adding `GetCACertPEM(ctx) (string, error)` to the issuer connector interface so the `/cacerts` endpoint can serve the CA chain. The Local CA returns its CA certificate PEM; Vault PKI fetches via `GET /v1/{mount}/ca/pem`; Google CAS fetches via API; AWS ACM PCA retrieves via `GetCertificateAuthorityCertificate`. ACME, step-ca, OpenSSL, DigiCert, and Sectigo connectors return errors (they don't expose a static CA chain — their chains are per-issuance).
 
+**Authentication:** EST endpoints are served unauthenticated at the HTTP layer under `/.well-known/est/*` — no Bearer token required. Per RFC 7030 §3.2.3 EST authentication is deployment-specific, and per §4.1.1 `/cacerts` is explicitly anonymous. certctl enforces authentication via CSR signature verification inside `ESTService.SimpleEnroll`/`SimpleReEnroll` plus profile policy gates (allowed key algorithms, minimum key size, permitted SANs, permitted EKUs, MaxTTL). The HTTP dispatch is implemented in `cmd/server/main.go:buildFinalHandler`, which routes `/.well-known/est/*` through `noAuthHandler` (RequestID + structuredLogger + Recovery only). Operators who need stronger client identification should terminate mTLS at an upstream reverse proxy and pin the CSR's SAN to the client cert subject at the profile level.
+
 **Audit:** Every EST enrollment is recorded in the audit trail with `protocol: "EST"`, the CN, SANs, issuer ID, serial number, and optional profile ID.
 
 ### SCEP Server (RFC 8894)
@@ -749,7 +751,7 @@ Signed certificate returned as PKCS#7 certs-only
 
 **Wire format:** SCEP clients wrap CSRs in PKCS#7 SignedData envelopes. The handler parses the outer ASN.1 ContentInfo → SignedData → EncapsulatedContentInfo to extract the CSR bytes. Fallback paths handle base64-encoded PKCS#7 and raw CSR submissions (for simpler clients). Responses use PKCS#7 certs-only via the shared `internal/pkcs7` package (same as EST). Single certs are returned as raw DER for `GetCACert`, chains as PKCS#7.
 
-**Authentication:** SCEP uses challenge passwords embedded in CSR attributes (OID 1.2.840.113549.1.9.7) rather than TLS client certificates. The server validates the challenge password against `CERTCTL_SCEP_CHALLENGE_PASSWORD`. When no challenge password is configured, any value is accepted.
+**Authentication:** SCEP endpoints at `/scep` and `/scep/*` are served unauthenticated at the HTTP layer — no Bearer token required — per RFC 8894 §3.2, which defines authentication via the `challengePassword` attribute (OID 1.2.840.113549.1.9.7) embedded in the PKCS#10 CSR rather than an HTTP credential. The HTTP dispatch is implemented in `cmd/server/main.go:buildFinalHandler`, which routes `/scep` and `/scep/*` through `noAuthHandler` (RequestID + structuredLogger + Recovery only). The `challengePassword` is mandatory: `preflightSCEPChallengePassword` at startup refuses to boot the control plane when `CERTCTL_SCEP_ENABLED=true` is set without `CERTCTL_SCEP_CHALLENGE_PASSWORD`, closing CWE-306 (missing authentication for a critical function). `SCEPService.PKCSReq` enforces the same invariant defense-in-depth — an empty `s.challengePassword` rejects every enrollment — and the password comparison uses `crypto/subtle.ConstantTimeCompare` to prevent response-time side-channel leakage. The startup log line `SCEP server enabled` emits a `challenge_password_set` boolean for operator visibility.
 
 **Interface:** The `SCEPHandler` defines an `SCEPService` interface (dependency inversion):
 
@@ -806,10 +808,11 @@ The control plane only handles public material: certificates, chains, and CSRs.
 
 ### Authentication
 
-- **API clients → Server**: API key in `Authorization: Bearer` header, or `none` for demo mode
+- **API clients → Server**: API key in `Authorization: Bearer` header, or `none` for demo mode. Applies to every path under `/api/v1/*`.
 - **Agent → Server**: API key registered at agent creation, included in all requests
 - **Server → Issuers**: ACME account key, or connector-specific credentials
 - **Agent → Targets**: API tokens, WinRM credentials (stored locally on agent or proxy agent — never on server). Credential scope is limited to the agent's network zone.
+- **Standards-based enrollment and PKI distribution endpoints**: `/.well-known/est/*` (RFC 7030), `/scep` and `/scep/*` (RFC 8894), and `/.well-known/pki/crl/{issuer_id}` + `/.well-known/pki/ocsp/{issuer_id}/{serial}` (RFC 5280 §5 / RFC 6960 / RFC 8615) are served unauthenticated at the HTTP layer. These protocols carry their own authentication semantics — CSR signature + profile policy for EST (§3.2.3 says EST auth is deployment-specific; §4.1.1 makes `/cacerts` explicitly anonymous), `challengePassword` in CSR attributes for SCEP (§3.2), and relying-party accessibility for CRL/OCSP — and cannot present certctl Bearer tokens. The dispatch is implemented in `cmd/server/main.go:buildFinalHandler`, which routes these prefixes through `noAuthHandler` (RequestID + structuredLogger + Recovery only, no auth or rate-limit middleware). CWE-306 is closed for SCEP by `preflightSCEPChallengePassword`, which refuses to start the server when SCEP is enabled without `CERTCTL_SCEP_CHALLENGE_PASSWORD`. The 27-subtest regression harness `cmd/server/finalhandler_test.go` pins this dispatch surface (EST 4-endpoint, SCEP exact + trailing-slash + query-string, PKI CRL+OCSP, health probes, `/api/v1/*` authenticated, `/assets/*` file server, SPA fallback).
 
 ### Audit Trail
 

docs/compliance-soc2.md

@@ -44,7 +44,8 @@ Each section includes:
 
 **certctl Implementation** (V2 — Community Edition):
 
-- **API Key Authentication** — All API calls require a Bearer token (hashed with SHA-256, stored securely, validated with constant-time comparison) or are rejected with 401 Unauthorized. Environment: `CERTCTL_AUTH_TYPE` (default `api-key`; `none` requires explicit opt-in with log warning)
+- **API Key Authentication** — All `/api/v1/*` calls require a Bearer token (hashed with SHA-256, stored securely, validated with constant-time comparison) or are rejected with 401 Unauthorized. Environment: `CERTCTL_AUTH_TYPE` (default `api-key`; `none` requires explicit opt-in with log warning)
+- **Standards-based enrollment and PKI distribution endpoints** — EST (`/.well-known/est/*`, RFC 7030), SCEP (`/scep`, `/scep/*`, RFC 8894), and CRL/OCSP (`/.well-known/pki/crl/{issuer_id}`, `/.well-known/pki/ocsp/{issuer_id}/{serial}`, RFC 5280 §5 / RFC 6960 / RFC 8615) are served unauthenticated at the HTTP layer because these protocols cannot present certctl Bearer tokens. Authentication is enforced in-protocol: EST relies on CSR signature verification plus profile policy (RFC 7030 §3.2.3 says EST auth is deployment-specific; §4.1.1 makes `/cacerts` explicitly anonymous); SCEP requires a shared `challengePassword` in the PKCS#10 CSR attributes (OID 1.2.840.113549.1.9.7, RFC 8894 §3.2), validated with `crypto/subtle.ConstantTimeCompare`; CRL and OCSP are intentionally anonymous for relying-party accessibility. CWE-306 (missing authentication for a critical function) is closed for SCEP by `preflightSCEPChallengePassword` in `cmd/server/main.go`, which refuses to start the control plane when `CERTCTL_SCEP_ENABLED=true` is set without `CERTCTL_SCEP_CHALLENGE_PASSWORD`. The HTTP dispatch is implemented in `cmd/server/main.go:buildFinalHandler`, which routes these prefixes through `noAuthHandler` (RequestID + structuredLogger + Recovery only, no auth or rate-limit middleware) and is pinned by the 27-subtest regression harness at `cmd/server/finalhandler_test.go`.
 - **GUI Authentication** — Web dashboard includes login screen requiring API key entry. Failed auth redirects to login on 401. Auth context persists across page navigation. Logout clears session.
 - **Configurable CORS** — API restricts cross-origin requests via `CERTCTL_CORS_ORIGINS` allowlist or wildcard. Preflight caching prevents chatty browser auth flows.
 - **Token Bucket Rate Limiting** — Per-IP rate limiting (configurable via `CERTCTL_RATE_LIMIT_RPS` / `CERTCTL_RATE_LIMIT_BURST`) returns 429 Too Many Requests with Retry-After header. Prevents credential stuffing and brute-force attacks.
@@ -58,6 +59,11 @@ Each section includes:
 - Auth info endpoint: `GET /api/v1/auth/info` (returns current auth mode, served without auth so GUI detects mode)
 - Rate limiting middleware: `internal/api/middleware/rate_limit.go`
 - CORS configuration: `cmd/server/main.go`, search for `CERTCTL_CORS_ORIGINS`
+- Final handler dispatch (authenticated vs. unauthenticated routing): `cmd/server/main.go:buildFinalHandler`
+- SCEP preflight gate (CWE-306 closure): `cmd/server/main.go:preflightSCEPChallengePassword`
+- SCEP service-layer defense-in-depth (rejects enrollment on empty challenge password, `crypto/subtle.ConstantTimeCompare`): `internal/service/scep.go`
+- Final handler dispatch regression harness (27 subtests): `cmd/server/finalhandler_test.go`
+- OpenAPI spec `security: []` overrides on unauthenticated paths: `api/openapi.yaml` (EST `/cacerts`, `/simpleenroll`, `/simplereenroll`, `/csrattrs`; SCEP `/scep` GET+POST; PKI `/crl/{issuer_id}`, `/ocsp/{issuer_id}/{serial}`)
 
 **V3 Enhancement**:
 
@@ -110,7 +116,7 @@ Each section includes:
 
 **certctl Implementation** (V2):
 
-- **API Key Policy** — All API access requires an API key or explicit opt-out. Opt-out (`CERTCTL_AUTH_TYPE=none`) logs a warning: "WARNING: Auth disabled (CERTCTL_AUTH_TYPE=none) — this is insecure and only for development". Configuration choice is logged at startup.
+- **API Key Policy** — All `/api/v1/*` access requires an API key or explicit opt-out. Opt-out (`CERTCTL_AUTH_TYPE=none`) logs a warning: "WARNING: Auth disabled (CERTCTL_AUTH_TYPE=none) — this is insecure and only for development". Configuration choice is logged at startup. The standards-based enrollment and PKI distribution endpoints (EST, SCEP, CRL, OCSP) are served unauthenticated at the HTTP layer per their respective RFCs; see CC6.1 for the full authentication contract and CWE-306 closure via `preflightSCEPChallengePassword`.
 - **Agent Authentication** — Agents authenticate to the server via API keys (same mechanism as users). Agent credentials are separate from user API keys.
 - **Private Key Policy** — Agent-side key generation is the default (`CERTCTL_KEYGEN_MODE=agent`). Server-side keygen (`CERTCTL_KEYGEN_MODE=server`) requires explicit configuration and logs a warning: "server-side key generation enabled (CERTCTL_KEYGEN_MODE=server) — private keys touch control plane, demo only".
 - **Password Policy** — Not applicable; certctl uses API keys exclusively. Password management is delegated to your organization's IAM system if you integrate OIDC/SSO (V3).