Backend Security Audit Checklist Implementation (#43)

[Adacancode]

Overview

Implements the backend security checklist items requested in issue #43:

• verifier role restrictions on verification endpoints
• idempotent validation transaction handling
• encryption of off-chain evidence at rest
• backend threat model assumptions documentation

Closes #43

Changes

Verification Security Controls

• [ADD] src/routes/verifications.ts

  • Added verification endpoints:
    • POST /api/verifications/validations
    • GET /api/verifications/validations
    • GET /api/verifications/validations/:id
  • Enforced authenticate + requireVerifier on all endpoints.
  • Added strict payload validation and Idempotency-Key requirement.
  • Returns:
    • 201 on first create
    • 200 on replay with same key + same payload
    • 409 on same key + different payload

• [ADD] src/services/verifications.ts

  • Added validation transaction service with idempotency index.
  • Added deterministic payload digesting for replay safety.
  • Added evidence encryption at rest using AES-256-GCM.
  • Evidence is stored encrypted; API returns metadata only.

App Wiring

• [MODIFY] src/app.ts

  • Registered /api/verifications router.
  • Centralized router wiring for transactions/privacy/verifications.
  • Enabled privacy logger in app bootstrap.

• [MODIFY] src/index.ts

  • Removed duplicated middleware/router setup and left server startup only.

Security/Privacy Hardening

• [MODIFY] src/middleware/privacy-logger.ts
  • Redacts sensitive fields recursively, including evidence payloads.

Documentation

• [ADD] docs/backend-threat-model.md

  • Added backend threat model assumptions, trust boundaries, implemented controls, and future hardening notes.

• [MODIFY] README.md

  • Added security controls section referencing verification protections and threat model doc.

• [MODIFY] .env.example

  • Added:
    • JWT_SECRET
    • EVIDENCE_ENCRYPTION_KEY

Tests

• [ADD] src/tests/verifications.test.ts
  • Verifies role restrictions across verification endpoints.
  • Verifies idempotent behavior and conflict semantics.
  • Verifies evidence is encrypted at rest (not stored in plaintext).

Baseline Fixes Needed for Valid Build/Test

• [MODIFY] src/routes/analytics.ts
  • Resolved duplicate/conflicting router declarations.
• [MODIFY] package.json
  • Fixed malformed JSON/scripts so test/build commands run.
• [MODIFY] package-lock.json
  • Regenerated during dependency install.

How to Run Tests

From repo root:

npm install
npm test
npm run build

Verification Results

Requirement	Status
Verifier role restrictions enforced in all verification endpoints	Done
Validation transactions are idempotent	Done
Evidence storage encrypted at rest	Done
Threat model assumptions documented	Done
Automated tests for new controls	Done
Build passes	Done

Verification Evidence

• npm test passed: 2 suites, 16 tests.
• npm run build passed.

[Adacancode]

@1nonlypiece review this sir

[1nonlypiece]

@Adacancode Can you resolve the conflicts?

[Adacancode]

@Adacancode Can you resolve the conflicts?

@1nonlypiece Done boss