# Implementation plan — Signer

## Delivery phases
- **Phase 1 – Core service & PoE**  
  Harden OpTok validation, Proof-of-Entitlement (PoE) checks, quota enforcement, scanner release verification, and DSSE signing pipeline (keyless + keyful).
- **Phase 2 – Export Center integration**  
  Produce signing bundles with provenance manifests for Export Center, deliver cosign-compatible outputs, and document verification workflows for offline exports.
- **Phase 3 – Attestor alignment**  
  Emit DSSE envelopes, metadata, and signer identity information required by Attestor (key metadata, certificate chains, bundle hashes); expose audit APIs.
- **Phase 4 – Observability & resilience**  
  Complete telemetry, throttling dashboards, audit trails, fallback key rotation, and offline kit packaging.

## Work breakdown
- **Authentication & entitlement**
  - Enforce Authority-issued DPoP/mTLS tokens with `signer.sign` scope and tenant checks.
  - Integrate PoE introspection (cloud licensing) and plan quotas.
  - Validate scanner release signature via OCI referrers before signing reports/SBOMs.
- **Signing pipeline**
  - Implement DSSE canonicalisation, keyless (Fulcio) and keyful (KMS/HSM/FIDO2) signing.
  - Support multi-signature output, certificate chain embedding, and deterministic bundle hashing.
  - Provide policy metadata (policy digest, view set) for report predicates.
- **Integrations**
  - Coordinate with Attestor on bundle schema, signer identity payload, and error codes.
  - Expose Export Center-ready signing API (`/sign/export`) that returns manifest + signature tuple.
  - Surface CLI flows (`stella sign sbom/report`, offline verification helpers).
- **Security & key management**
  - Key rotation and revocation runbooks; separation of signing keys per tenancy/plan.
  - Hardware-backed key support (HSM/FIDO2) with audit logging and attested builds.
- **Observability**
  - Metrics: signing latency, PoE failures, quota hits, key usage distribution.
  - Structured logs with trace/context IDs, subject digests, issuer mode, decision outcome.
  - Alerts for PoE outages, key exhaustion, quota breach, signing failure spikes.
- **Documentation & runbooks**
  - Update README/architecture/implementation plan, operator runbooks, offline verification guidance, and CLI reference.

## Acceptance criteria
- Signer only signs requests that satisfy OpTok, PoE, quota, and scanner provenance checks.
- DSSE outputs (keyless + keyful) verify with standard cosign tooling; Attestor logs them without additional transformation.
- Export Center receives signed bundles, provenance manifests, and signature metadata to package exports deterministically.
- Audit logs capture every signing request with tenant, issuer, subject digest, PoE state, and key source.
- Observability dashboards/alerts reflect latency, failure rate, PoE status, and quota usage.
- CLI/Offline workflows verify signatures using Offline Kit trust roots.

## Risks & mitigations
- **PoE/entitlement outages:** cache last-known entitlement within TTL, provide emergency bypass toggles with audit trail.
- **Key compromise:** enforce hardware-backed keys, rotation cadence, immediate revocation workflow, incident runbook.
- **Release verification failures:** maintain allowlist for trusted scanner digests, fallback to manual approval with audit.
- **Determinism drift:** canonicalise JSON, lock timestamp sources, regression tests for DSSE hashing.

## Test strategy
- **Unit:** OpTok/PoE validation, quota enforcement, scanner signature verification, DSSE canonicalisation, multi-sig bundling.
- **Integration:** end-to-end signing for SBOM, report, export artifacts; Attestor ingestion; Export Center bundle signing.
- **Security:** fuzz signing inputs, simulate PoE tampering, ensure unauthorized actors are rejected.
- **Performance:** signing throughput benchmarks (keyless vs keyful), quota pressure, concurrency checks.
- **Offline:** verify signatures using Offline Kit trust roots and cosign CLI without network access.

## Definition of done
- Signing pipeline deployed with observability and incident runbooks.
- Export Center + Attestor dependencies validated; CLI parity confirmed.
- Documentation updated (README, architecture, runbooks, CLI guides) with imposed rule compliance.
- ./TASKS.md and ../../TASKS.md reflect the latest status transitions.

---

## Sprint readiness tracker

> Last updated: 2025-11-27 (SIGNER-ENG-0001)

This section maps delivery phases to implementation sprints and tracks readiness checkpoints.

### Phase 1 — Core service & PoE
| Task ID | Status | Sprint | Notes |
|---------|--------|--------|-------|
| KMSI-73-001 | ✅ DONE (2025-11-03) | SPRINT_100_identity_signing | KMS key management foundations with staffing + DSSE contract. |
| KMSI-73-002 | ✅ DONE (2025-11-03) | SPRINT_100_identity_signing | FIDO2 profile integration. |
| PROV-OBS-53-001 | ✅ DONE (2025-11-17) | SPRINT_0513_0001_0001_provenance | DSSE/SLSA BuildDefinition + BuildMetadata models with canonical JSON serializer. |
| PROV-OBS-53-002 | ✅ DONE (2025-11-23) | SPRINT_0513_0001_0001_provenance | Signer abstraction (cosign/KMS/offline) with key rotation hooks and audit logging. |
| SEC-CRYPTO-90-020 | 🔄 IN PROGRESS | SPRINT_0514_0001_0001_sovereign_crypto | CryptoPro signer plugin; Windows CSP runner pending. |

**Checkpoint:** Core signing infrastructure operational — KMS drivers, signer abstractions, and DSSE models delivered.

### Phase 2 — Export Center integration
| Task ID | Status | Sprint | Notes |
|---------|--------|--------|-------|
| PROV-OBS-53-003 | ✅ DONE (2025-11-23) | SPRINT_0513_0001_0001_provenance | PromotionAttestationBuilder feeding canonicalised payloads to Signer. |
| SIGN-REPLAY-186-003 | 📝 TODO | SPRINT_186_record_deterministic_execution | Extend Signer/Authority DSSE flows for replay manifest/bundle payloads. |
| SIGN-CORE-186-004 | 📝 TODO | SPRINT_186_record_deterministic_execution | Replace HMAC demo with StellaOps.Cryptography providers (keyless + KMS). |
| SIGN-CORE-186-005 | 📝 TODO | SPRINT_186_record_deterministic_execution | Refactor SignerStatementBuilder for StellaOps predicate types. |
| SIGN-TEST-186-006 | 📝 TODO | SPRINT_186_record_deterministic_execution | Upgrade signer integration tests with real crypto + fixture predicates. |

**Checkpoint:** Export Center signing APIs partially complete; replay manifest support and crypto provider refactoring pending.

### Phase 3 — Attestor alignment
| Task ID | Status | Sprint | Notes |
|---------|--------|--------|-------|
| AUTH-REACH-401-005 | 📝 TODO | SPRINT_0401_0001_0001_reachability_evidence_chain | DSSE predicate types for SBOM/Graph/VEX/Replay; blocked on predicate definitions. |
| SIGN-VEX-401-018 | 📝 TODO | SPRINT_0401_0001_0001_reachability_evidence_chain | Extend predicate catalog with `stella.ops/vexDecision@v1`. |
| PROV-OBS-54-001 | 📝 TODO | SPRINT_0513_0001_0001_provenance | Verification library for DSSE signatures, Merkle roots, timeline chain. |
| PROV-OBS-54-002 | 📝 TODO | SPRINT_0513_0001_0001_provenance | .NET global tool for local verification + CLI `stella forensic verify`. |

**Checkpoint:** Attestor DSSE alignment pending; predicate catalog extension and verification library not started.

### Phase 4 — Observability & resilience
| Task ID | Status | Sprint | Notes |
|---------|--------|--------|-------|
| DOCS-PROMO-70-001 | 📝 TODO | SPRINT_304_docs_tasks_md_iv | Promotion attestations doc (CLI commands, Signer/Attestor integration, offline verification). |
| CLI-PROMO-70-002 | 📝 TODO | SPRINT_203_cli_iii | `stella promotion attest` / `promotion verify` commands. |
| CLI-FORENSICS-54-002 | 📝 TODO | SPRINT_202_cli_ii | `stella forensic attest show <artifact>` listing signer details. |

**Checkpoint:** Observability and CLI integration pending; waiting on upstream signing pipeline completion.

---

### Overall readiness summary

| Phase | Status | Blocking items |
|-------|--------|----------------|
| **1 – Core service & PoE** | ✅ Complete | — |
| **2 – Export Center integration** | 🔄 In progress | SIGN-CORE-186-004/005 crypto provider refactoring |
| **3 – Attestor alignment** | 📝 Not started | AUTH-REACH-401-005 predicate definitions |
| **4 – Observability & resilience** | 📝 Not started | Upstream phase completion |

### Cross-module dependencies

| Dependency | Required by | Status |
|------------|-------------|--------|
| Attestor DSSE bundle schema | SIGN-VEX-401-018 | Documented in `docs/modules/attestor/architecture.md` §1 |
| Provenance library canonicalisation | SIGN-CORE-186-005 | Available via PROV-OBS-53-001/002 |
| Export Center bundle manifest | SIGN-REPLAY-186-003 | Pending Sprint 162/163 deliverables |
| Authority predicate definitions | AUTH-REACH-401-005 | Schema draft pending |

### Next actions
1. Complete CryptoPro signer plugin Windows smoke test (SEC-CRYPTO-90-020, Sprint 0514).
2. Start SIGN-CORE-186-004 once replay bundle schema finalises (Sprint 186).
3. Track AUTH-REACH-401-005 predicate schema draft for Attestor alignment (Sprint 401).
4. Monitor PROV-OBS-54-001/002 for verification library availability.