# Key Rotation Service with Temporal Validity

## Module
Signer

## Status
VERIFIED

## Description
Automated key rotation service with temporal key validity windows, key history tracking (key_history and key_audit_log tables), trust anchor management with PURL pattern matching, and CLI commands for key lifecycle operations. Ensures proof verification uses the correct key for the attestation timestamp.

## Implementation Details
- **KeyRotationService**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/KeyRotationService.cs` -- implements advisory section 8.2: AddKeyAsync (validates algorithm against AllowedAlgorithms, creates KeyHistoryEntity + KeyAuditLogEntity, updates anchor AllowedKeyIds), RevokeKeyAsync (sets RevokedAt + RevokeReason, moves key from AllowedKeyIds to RevokedKeyIds), CheckKeyValidityAsync (temporal validation: NotYetValid if signedAt < AddedAt, Revoked if signedAt >= RevokedAt, Expired if signedAt >= ExpiresAt), GetRotationWarningsAsync (ExpiryApproaching within ExpiryWarningDays, LongLived exceeding MaxKeyAgeDays, AlgorithmDeprecating for deprecated algorithms), GetKeyHistoryAsync; EF Core transactions with InMemory provider detection
- **TrustAnchorManager**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/TrustAnchorManager.cs` -- implements advisory section 8.3: GetAnchorAsync, FindAnchorForPurlAsync (glob-style PURL pattern matching with specificity scoring, most-specific-match-wins), CreateAnchorAsync (validates PURL pattern), UpdateAnchorAsync (AllowedPredicateTypes/PolicyRef/PolicyVersion), DeactivateAnchorAsync, VerifySignatureAuthorizationAsync (combines temporal key validity + predicate type authorization), GetActiveAnchorsAsync
- **PurlPatternMatcher**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/TrustAnchorManager.cs` -- glob-to-regex pattern matching for PURLs (e.g., pkg:npm/*, pkg:maven/org.apache/*); specificity scoring (segments * 10 - wildcards * 5)
- **KeyRotationOptions**: configurable AllowedAlgorithms (ES256, ES384, ES512, RS256, EdDSA, SM2, GOST12-256, DILITHIUM3, FALCON512, etc.), ExpiryWarningDays (60), MaxKeyAgeDays (365), DeprecatedAlgorithms (RSA-2048, SHA1-RSA)
- **KeyManagementDbContext**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/KeyManagementDbContext.cs` -- EF Core context with TrustAnchors, KeyHistory, KeyAuditLog DbSets
- **KeyEntities**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/Entities/KeyEntities.cs` -- KeyHistoryEntity (HistoryId, AnchorId, KeyId, PublicKey, Algorithm, AddedAt, ExpiresAt, RevokedAt, RevokeReason), KeyAuditLogEntity (LogId, Operation enum: Add/Revoke/Rotate, Actor, Reason)
- **TrustAnchorEntity**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/Entities/TrustAnchorEntity.cs` -- AnchorId, PurlPattern, AllowedKeyIds, RevokedKeyIds, AllowedPredicateTypes, PolicyRef, PolicyVersion, IsActive
- **KeyRotationEndpoints**: `src/Signer/StellaOps.Signer/StellaOps.Signer.WebService/Endpoints/KeyRotationEndpoints.cs` -- REST API at `/api/v1/anchors`: POST /{anchorId}/keys (add key), POST /{anchorId}/keys/{keyId}/revoke, GET /{anchorId}/keys/{keyId}/validity?signedAt=, GET /{anchorId}/keys/history, GET /{anchorId}/keys/warnings; all require KeyManagement authorization
- **IKeyRotationService**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/IKeyRotationService.cs` -- interface contract
- **ITrustAnchorManager**: `src/Signer/__Libraries/StellaOps.Signer.KeyManagement/ITrustAnchorManager.cs` -- interface contract
- **Tests**: `src/Signer/StellaOps.Signer/StellaOps.Signer.Tests/KeyManagement/KeyRotationServiceTests.cs`, `TemporalKeyVerificationTests.cs`, `TrustAnchorManagerTests.cs`, `Integration/KeyRotationWorkflowIntegrationTests.cs`
- **Source**: SPRINT_0501_0008_0001_proof_chain_key_rotation.md

## E2E Test Plan
- [x] POST /api/v1/anchors/{anchorId}/keys adds a key and returns updated AllowedKeyIds with audit log ID
- [x] POST /{anchorId}/keys/{keyId}/revoke sets RevokedAt and moves key from allowed to revoked list
- [x] GET /{anchorId}/keys/{keyId}/validity returns correct temporal validity (Active, NotYetValid, Revoked, Expired) for a given signedAt timestamp
- [x] Verify temporal key validation: key added at T1 is invalid for signatures before T1, valid between T1 and revocation/expiry
- [x] GET /{anchorId}/keys/warnings returns ExpiryApproaching, LongLived, and AlgorithmDeprecating warnings
- [x] Verify PURL pattern matching finds most-specific anchor for a given PURL
- [x] Verify VerifySignatureAuthorizationAsync combines key validity + predicate type check
- [x] Verify algorithm validation rejects keys with unsupported algorithms

## Verification
- **Run ID**: run-001
- **Date**: 2026-02-10
- **Method**: Tier 1 code review + Tier 2d existing test verification
- **Build**: PASS (0 errors, 0 warnings)
- **Tests**: PASS (491/491 signer tests pass)
- **Code Review**:
  - KeyRotationService: Full temporal key lifecycle verified. AddKeyAsync validates algorithm against configurable AllowedAlgorithms list, creates KeyHistoryEntity + KeyAuditLogEntity in EF Core transaction. CheckKeyValidityAsync implements correct temporal precedence: NotYetValid (signedAt < AddedAt) > Revoked (signedAt >= RevokedAt) > Expired (signedAt >= ExpiresAt) > Active. GetRotationWarningsAsync checks three warning types with configurable thresholds.
  - TrustAnchorManager: PURL pattern matching verified -- glob-to-regex conversion, specificity scoring (segments*10 - wildcards*5), most-specific-match-wins semantics. VerifySignatureAuthorizationAsync correctly combines temporal key validity with predicate type authorization.
  - Tests: KeyRotationServiceTests (add/revoke/validity checks), TemporalKeyVerificationTests (boundary conditions for temporal validation), TrustAnchorManagerTests (PURL matching, specificity scoring), KeyRotationWorkflowIntegrationTests (end-to-end rotation workflows with EF Core InMemory provider).
- **Verdict**: PASS

## Recheck (Run-002)
- **Verified**: 2026-02-10
- **Method**: Tier 2a live API replay + Tier 1 regression suite replay.
- **Tests**: PASS (496/496 signer tests pass).
- **Tier 2 Evidence**: `docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-002/tier2-api-check.json`
- **Regression Coverage Added**: `KeyValidity_ReturnsNotFound_ForUnknownAnchorOrKey`.
- **Outcome**: Unknown key validity lookups now return `404 Not Found` instead of `200 Unknown`.

## Recheck (Run-003)
- **Verified**: 2026-02-10
- **Method**: Tier 2 follow-up deterministic replay.
- **Tests**: PASS (`src/Signer/StellaOps.Signer/StellaOps.Signer.Tests`: 496/496).
- **Tier 2 Evidence**: `docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-003/tier2-api-check.json`
- **Outcome**: Key-validity and temporal semantics remain stable, including unknown-key 404 handling.


## Recheck (Run-004)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay + full Signer suite replay.
- **Tests**: PASS (`src/Signer/StellaOps.Signer/StellaOps.Signer.Tests`: 496/496).
- **Tier 2 Evidence**: `docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-004/tier2-api-check.json`
- **Outcome**: Key-validity API behavior (including unknown-key semantics) remains stable.

## Recheck (Run-005)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay validated via Signer suite and endpoint coverage.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-005/tier2-api-check.json
- **Outcome**: Checked signer behavior remains healthy in follow-up replay.

## Recheck (Run-006)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay (API + integration) with deterministic signer suite verification.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-006/tier2-api-check.json
- **Outcome**: Checked signer behavior remains healthy in continued replay.

## Recheck (Run-007)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay (API + integration) with deterministic signer suite verification.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-007/tier2-api-check.json
- **Outcome**: Checked signer behavior remains healthy in continued replay.

## Recheck (Run-008)
- **Verified**: 2026-02-10
- **Method**: Tier 2a API replay + deterministic integration suite replay.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-008/tier2-api-check.json
- **Outcome**: Checked Signer behavior remains healthy in continued replay.


## Recheck (Run-009)
- **Verified**: 2026-02-10
- **Method**: Tier 2a API replay + deterministic integration suite replay.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-009/tier2-api-check.json
- **Outcome**: Checked Signer behavior remains healthy in continued replay.


## Recheck (Run-010)
- **Verified**: 2026-02-10
- **Method**: Tier 2d deterministic integration replay.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-010/tier2-integration-check.json
- **Outcome**: Checked signer behavior remains healthy in continued replay.
## Recheck (Run-011)
- **Verified**: 2026-02-10
- **Method**: Tier 2d deterministic integration replay.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-011/tier2-integration-check.json
- **Outcome**: Checked signer behavior remains healthy in continued replay.
## Recheck (Run-012)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay + deterministic integration suite replay.
- **Tests**: PASS (src/Signer/StellaOps.Signer/StellaOps.Signer.Tests: 496/496).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/signer/key-rotation-service-with-temporal-validity/run-012/tier2-api-check.json
- **Outcome**: Checked signer behavior remains healthy in continued replay.