[ashishsinghbora]

Summary

Implements Stage 6: Verifiable Credentials & Cryptographic Infrastructure (Milestone 5) to upgrade TechNexus credentials into tamper-evident, cryptographically verifiable credentials backed by asymmetric Ed25519 digital signatures and public JWKS key discovery.

Closes #19

Architectural Invariants & Key Changes

1. Cryptographic Engine (src/lib/credentials/crypto.ts):

   • Asymmetric Ed25519 digital signatures using Node.js built-in cryptography.
   • Deterministic JSON canonicalization (canonicalize) producing stable digests across key insertion order.
   • SHA-256 canonical digest computation and payload signing.
   • Key rotation support with Key IDs (kid: tn-ed25519-2026-v1).
   • Signature validation with strict tamper rejection.

2. Public Key Discovery Endpoint (src/app/api/verify/keys/route.ts):

   • Publicly accessible JWKS discovery endpoint delivering public keys (kty: OKP, crv: Ed25519, alg: EdDSA) for institutional verification by universities, employers, and scanners.
   • Configured with HTTP cache headers (Cache-Control: public, max-age=3600).

3. Database Schema & Migrations (drizzle/0009_cryptographic_credentials.sql):

   • Expanded type enum in credentials table to include:
     • learning_track_completion
     • internship_completion
     • cohort_completion
   • Added signature, signing_key_id, and canonical_hash columns.

4. Credential Engine Upgrade (src/lib/credentials/engine.ts):

   • Introduced issueVerifiableCredential automating Ed25519 signature computation over canonical claims.
   • Updated metadata builders for fellowship and curriculum track graduation.

5. Institutional Verification UI (src/app/verify/[id]/page.tsx):

   • Displays cryptographic verification card showing verified Ed25519 signature badge, Key ID, and canonical SHA-256 hash.
   • Tailored evidence views for GitHub PRs, curriculum tracks, and fellowship mentors.
   • Dedicated print / PDF certificate generation button (PrintButton.tsx) with print-optimized CSS.

Verification

• Automated Tests: 110/110 tests passing across 25 test files (npm test).
• Type Checking: Clean pass with zero errors (npm run typecheck).
• Linting: Clean pass with zero errors/warnings (npm run lint).
• Production Build: 27/27 routes compiled successfully (npm run build).

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