# Enhanced Rekor Proof Building with Inclusion Proofs

## Module
Attestor

## Status
VERIFIED

## Description
Full Rekor proof builder with build, validate, and inclusion proof types for transparency log verification.

## Implementation Details
- **Enhanced Rekor Proof Builder**: `src/Attestor/__Libraries/StellaOps.Attestor.ProofChain/Rekor/EnhancedRekorProofBuilder.cs` -- main builder class with partials:
  - `.Build` -- constructs Rekor proofs from transparency log entries
  - `.Validate` -- validates proof integrity
- **Enhanced Rekor Proof**: `Rekor/EnhancedRekorProof.cs` -- proof model with inclusion proof and verification data.
- **Rekor Inclusion Proof**: `Rekor/RekorInclusionProof.cs` -- Merkle inclusion proof for transparency log entries.
- **Rekor Integration**: `Pipeline/RekorEntry.cs` -- Rekor entry in the proof chain pipeline.
- **Merkle Proof Verifier**: `StellaOps.Attestor.Core/Verification/MerkleProofVerifier.cs` -- verifies Merkle inclusion proofs.
- **Rekor Verification Service**: `StellaOps.Attestor.Core/Verification/RekorVerificationService.cs`, `IRekorVerificationService.cs` -- orchestrates Rekor verification.
- **Offline Receipt Verifier**: `StellaOps.Attestor.Core/Verification/RekorOfflineReceiptVerifier.cs` -- verifies Rekor receipts offline.
- **Verification Pipeline Step**: `__Libraries/StellaOps.Attestor.ProofChain/Verification/RekorInclusionVerificationStep.cs` -- pipeline step for inclusion proof verification.
- **Tests**: `__Tests/StellaOps.Attestor.Types.Tests/Rekor/RekorInclusionProofTests.cs`, `StellaOps.Attestor.Core.Tests/Rekor/RekorReceiptTests.cs`, `__Tests/StellaOps.Attestor.Conformance.Tests/InclusionProofParityTests.cs`

## E2E Test Plan
- [ ] Build an enhanced Rekor proof via `EnhancedRekorProofBuilder.Build` from a transparency log entry and verify the proof contains an inclusion proof
- [ ] Validate the proof via `EnhancedRekorProofBuilder.Validate` and verify it passes
- [ ] Verify the inclusion proof via `MerkleProofVerifier` and confirm the computed root matches the checkpoint root
- [ ] Verify a Rekor receipt offline via `RekorOfflineReceiptVerifier` using embedded inclusion proof
- [ ] Run `RekorInclusionVerificationStep` in the verification pipeline and verify it passes for valid entries
- [ ] Tamper with the inclusion proof sibling hashes and verify verification fails
- [ ] Run conformance parity tests to verify inclusion proof verification matches reference implementation

## Verification

| Check | Result |
|-------|--------|
| Tier 0 - Source Verification | PASS |
| Tier 1 - Build + Code Review | PASS |
| Tier 2 - Behavioral Verification | PASS |
| Verified Date | 2026-02-13 |
| Run ID | run-001 |