# StellaOps Signer

Signer validates callers, enforces Proof-of-Entitlement, and produces signed DSSE bundles for SBOMs, reports, and exports.

## Latest updates (Sprint 0186/0401 · 2025-11-26)
- **CryptoDsseSigner** implemented with ICryptoProviderRegistry integration (SIGN-CORE-186-004), enabling keyless + KMS signing modes with cosign-compatible DSSE output.
- **SignerStatementBuilder** refactored to support StellaOps predicate types (`stella.ops/promotion@v1`, `stella.ops/sbom@v1`, `stella.ops/vex@v1`, etc.) with CanonicalJson canonicalization (SIGN-CORE-186-005).
- **PredicateTypes catalog** extended with `stella.ops/vexDecision@v1` and `stella.ops/graph@v1` for reachability evidence chain (SIGN-VEX-401-018).
- **Helper methods** added: `IsVexRelatedType`, `IsReachabilityRelatedType`, `GetAllowedPredicateTypes`, `IsAllowedPredicateType` for predicate type validation.
- **Integration tests** upgraded with real crypto abstraction, fixture predicates (promotion, SBOM, VEX, replay, policy, evidence, graph), and deterministic test data (SIGN-TEST-186-006). All 102 Signer tests passing.

## Previous updates (Sprint 11 · 2025-10-21)
- `/sign/dsse` pipeline landed with Authority OpTok + PoE enforcement, Fulcio/KMS signing modes, and deterministic DSSE bundles ready for Attestor logging.
- `/verify/referrers` endpoint exposes release-integrity checks against scanner OCI referrers so callers can confirm digests before requesting signatures.
- Plan quota enforcement (QPS/concurrency/artifact size) and audit/metrics wiring now align with the Sprint 11 signing-chain release.

## Responsibilities
- Enforce Proof-of-Entitlement and plan quotas before signing artifacts.
- Support keyless (Fulcio) and keyful (KMS/HSM) signing backends.
- Verify scanner release integrity via OCI referrers prior to issuing signatures.
- Emit DSSE payloads consumed by Attestor/Export Center and maintain comprehensive audit trails.

## Key components
- `StellaOps.Signer` service host with `SignerPipeline` orchestrating the signing flow.
- `CryptoDsseSigner` for ES256 signature generation via `ICryptoProviderRegistry`.
- `SignerStatementBuilder` for in-toto statement creation with `PredicateTypes` catalog.
- `DefaultSigningKeyResolver` for tenant-aware key resolution (keyless/KMS modes).
- Crypto providers under `StellaOps.Cryptography.*`.

## Integrations & dependencies
- Authority for OpTok + PoE validation.
- Licensing Service for entitlement introspection.
- OCI registries (Referrers API) for scanner release verification.
- Attestor for transparency logging and Rekor ingestion.
- Export Center and CLI for artifact signing flows.

## API quick reference
- `POST /api/v1/signer/sign/dsse` — validate OpTok/PoE, enforce quotas, return DSSE bundle with signing identity metadata.
- `GET /api/v1/signer/verify/referrers` — report scanner release signer and trust verdict for a supplied image digest.

## Operational notes
- Key management via Authority/DevOps runbooks.
- Metrics for signing latency/throttle states.
- Offline kit integration for signature verification.

## Backlog references
- Sprint 0186: `docs/implplan/SPRINT_0186_0001_0001_record_deterministic_execution.md` (SIGN-CORE-186-004, SIGN-CORE-186-005, SIGN-TEST-186-006 DONE; SIGN-REPLAY-186-003 blocked on upstream).
- Sprint 0401: `docs/implplan/SPRINT_0401_0001_0001_reachability_evidence_chain.md` (SIGN-VEX-401-018 DONE; AUTH-REACH-401-005 TODO).
- SIG docs/tasks in ../../TASKS.md (e.g., DOCS-SIG-26-006).

## Implementation Status

### Phase 1 – Core service & PoE (Complete)
- OpTok validation with Authority DPoP/mTLS tokens and signer.sign scope
- Proof-of-Entitlement (PoE) introspection with cloud licensing integration
- Scanner release verification via OCI referrers
- DSSE signing pipeline: keyless (Fulcio) and keyful (KMS/HSM/FIDO2)
- KMS key management foundations (KMSI-73-001, KMSI-73-002)
- DSSE/SLSA BuildDefinition models with canonical JSON (PROV-OBS-53-001/002)

### Phase 2 – Export Center integration (In Progress)
- CryptoDsseSigner with ICryptoProviderRegistry (keyless + KMS modes)
- SignerStatementBuilder refactored for StellaOps predicate types
- PromotionAttestationBuilder with canonicalized payloads (PROV-OBS-53-003)
- Cosign-compatible DSSE output with provenance manifests
- Blocking: SIGN-CORE-186-004/005 crypto provider refactoring, replay manifest support

### Phase 3 – Attestor alignment (Not Started)
- DSSE envelope metadata for Attestor ingestion
- Extended predicate catalog: stella.ops/vexDecision@v1, stella.ops/graph@v1 (SIGN-VEX-401-018 complete)
- Helper methods: IsVexRelatedType, IsReachabilityRelatedType, predicate validation
- Blocking: AUTH-REACH-401-005 predicate definitions, verification library (PROV-OBS-54-001/002)

### Phase 4 – Observability & resilience (Not Started)
- Metrics: signing latency, PoE failures, quota hits, key usage distribution
- Structured logs with trace IDs, subject digests, issuer mode, decision outcomes
- Alerts for PoE outages, key exhaustion, quota breaches, failure spikes
- CLI commands: stella promotion attest/verify, stella forensic attest show

### Key Acceptance Criteria
- Signs only requests satisfying OpTok, PoE, quota, scanner provenance checks
- DSSE outputs verify with standard cosign tooling
- Export Center receives signed bundles with provenance manifests
- Audit logs capture every request with tenant, issuer, subject digest, PoE state
- CLI/Offline workflows verify signatures using Offline Kit trust roots

### Technical Decisions & Risks
- PoE/entitlement outages: cache last-known entitlement within TTL, emergency bypass with audit
- Key compromise: hardware-backed keys, rotation cadence, immediate revocation, incident runbook
- Release verification failures: allowlist for trusted scanner digests, manual approval fallback
- Determinism: canonicalize JSON, lock timestamp sources, regression tests for DSSE hashing

### Recent Updates (Sprint 0186/0401 · 2025-11-26)
- CryptoDsseSigner with ES256 signature generation via ICryptoProviderRegistry
- PredicateTypes catalog extended with VEX/graph predicates
- Integration tests upgraded with real crypto, fixture predicates (102 tests passing)
- CryptoPro signer plugin in progress (SEC-CRYPTO-90-020)

## Epic alignment
- **Epic 10 – Export Center:** provide signing pipelines, cosign interoperability, and provenance manifests for bundle promotion.
- **Epic 19 – Attestor Console:** supply DSSE payloads and Proof-of-Entitlement enforcement feeding attestation workflows described in `docs/modules/attestor/`.