# Evidence Locker Attestation Contract (v1 · frozen 2025-11-20)

Scope: Evidence Bundle v1 produced by Evidence Locker and consumed by Concelier, Excititor, Export Center, CLI, and Policy Engine.

## Predicates & subjects
- **Subject**: OCI manifest digest (`sha256:<digest>`) of the bundle, plus optional replay pack digest.
- **Predicates (DSSE/In-Toto)**
  - `stellaops.evidence.bundle.v1`: declares bundle layout (manifests, CAS paths, replay log offsets).
  - `stellaops.evidence.transparency.v1`: optional Rekor log inclusion proof (UUID, log index, root hash at inclusion).
  - `stellaops.evidence.integrity.v1`: hashes for each payload (SBOMs, VEX, policy packs, telemetry snapshots), keyed by logical path.

## Required claim set
- `bundle_id` (UUID v4)
- `produced_at` (UTC ISO-8601)
- `producer` (`evidence-locker:<region>`)
- `subject_digest` (OCI digest string)
- `hashes` (map: logical path → sha256)
- `sbom` (array of SPDX/CycloneDX digests and mediaTypes)
- `vex` (array of VEX doc digests and schema versions)
- `replay_manifest` (optional; digest + sequence number)
- `transparency` (optional; Rekor UUID, logIndex, rootHash)
- `signing_profile` (`sovereign-default` | `fips` | `gost` | `pq-experimental`)

## Bundling & signing rules
- DSSE envelope using the module’s configured crypto provider; keys must be short-lived (<24h) and recorded in provider registry.
- Hash list and subject digest MUST match the on-disk CAS objects; deterministic sort by logical path.
- Rekor entry is optional; when absent, set `transparency=null` and add `transparency_reason="offline"` to provenance note.

## Verification plan
- Verify DSSE signature against provider registry (per profile) and check key expiry.
- Recompute sha256 for every CAS object; fail if any mismatch.
- If `transparency` present, verify inclusion proof against bundled Rekor root; fail closed on mismatch.
- Emit verification report JSON and store beside bundle as `verify.json` (deterministic key order).

## Fixtures
- Sample bundle + report: `docs/samples/evidence-locker/bundle-v1-sample.tar.gz` (sha256 TBD at publish time).
- Sample attestation envelope: `docs/samples/evidence-locker/attestation-v1-sample.json`.

## Ownership
- Primary: Evidence Locker Guild.
- Reviewers: Concelier Core Guild, Excititor Guild, Export Center Guild, Policy Guild.

This contract is authoritative for Sprint 110 and blocks CONCELIER-ATTEST-73-001/002 and EXCITITOR-ATTEST-01-003/73-001/73-002.