feat(passenger-api): add pkce and client-assertion utilities for fayda

apps/edr-passenger-api/package.json

@@ -36,7 +36,7 @@
     "bcrypt": "^5.1.1",
     "class-transformer": "^0.5.1",
     "class-validator": "^0.14.0",
-    "jose": "^6.2.3",
+    "jose": "^5.10.0",
     "passport": "^0.7.0",
     "passport-jwt": "^4.0.1",
     "qrcode": "^1.5.3",

apps/edr-passenger-api/src/modules/verifayda/utils/client-assertion.util.spec.ts

@@ -0,0 +1,71 @@
+import { exportJWK, generateKeyPair, importJWK, jwtVerify, type JWK } from 'jose';
+import { generateClientAssertion } from './client-assertion.util';
+
+describe('generateClientAssertion', () => {
+  let privateJwk: JWK;
+  let publicJwk: JWK;
+
+  beforeAll(async () => {
+    const kp = await generateKeyPair('RS256', { extractable: true });
+    privateJwk = await exportJWK(kp.privateKey);
+    publicJwk = await exportJWK(kp.publicKey);
+  });
+
+  it('produces a JWT verifiable with the matching public key', async () => {
+    const jwt = await generateClientAssertion({
+      clientId: 'edr-passenger-test',
+      audience: 'https://esignet.example.com/token',
+      privateJwk,
+    });
+
+    const verifier = await importJWK(publicJwk, 'RS256');
+    const { payload, protectedHeader } = await jwtVerify(jwt, verifier, {
+      issuer: 'edr-passenger-test',
+      subject: 'edr-passenger-test',
+      audience: 'https://esignet.example.com/token',
+    });
+
+    expect(protectedHeader.alg).toBe('RS256');
+    expect(protectedHeader.typ).toBe('JWT');
+    expect(payload.iss).toBe('edr-passenger-test');
+    expect(payload.sub).toBe('edr-passenger-test');
+    expect(payload.aud).toBe('https://esignet.example.com/token');
+    expect(typeof payload.iat).toBe('number');
+    expect(typeof payload.exp).toBe('number');
+  });
+
+  it('defaults exp to 120 seconds after iat', async () => {
+    const jwt = await generateClientAssertion({
+      clientId: 'c',
+      audience: 'https://a/token',
+      privateJwk,
+    });
+    const verifier = await importJWK(publicJwk, 'RS256');
+    const { payload } = await jwtVerify(jwt, verifier);
+    expect(payload.exp! - payload.iat!).toBe(120);
+  });
+
+  it('honors a custom expiresIn', async () => {
+    const jwt = await generateClientAssertion({
+      clientId: 'c',
+      audience: 'https://a/token',
+      privateJwk,
+      expiresIn: '5m',
+    });
+    const verifier = await importJWK(publicJwk, 'RS256');
+    const { payload } = await jwtVerify(jwt, verifier);
+    expect(payload.exp! - payload.iat!).toBe(300);
+  });
+
+  it('fails verification against a wrong audience', async () => {
+    const jwt = await generateClientAssertion({
+      clientId: 'c',
+      audience: 'https://a/token',
+      privateJwk,
+    });
+    const verifier = await importJWK(publicJwk, 'RS256');
+    await expect(
+      jwtVerify(jwt, verifier, { audience: 'https://other/token' }),
+    ).rejects.toThrow();
+  });
+});

apps/edr-passenger-api/src/modules/verifayda/utils/client-assertion.util.ts

@@ -0,0 +1,22 @@
+import { SignJWT, importJWK, type JWK } from 'jose';
+
+export interface GenerateClientAssertionInput {
+  clientId: string;
+  audience: string;
+  privateJwk: JWK;
+  expiresIn?: string;
+}
+
+export async function generateClientAssertion(
+  input: GenerateClientAssertionInput,
+): Promise<string> {
+  const privateKey = await importJWK(input.privateJwk, 'RS256');
+  return new SignJWT({})
+    .setProtectedHeader({ alg: 'RS256', typ: 'JWT' })
+    .setIssuer(input.clientId)
+    .setSubject(input.clientId)
+    .setAudience(input.audience)
+    .setIssuedAt()
+    .setExpirationTime(input.expiresIn ?? '2m')
+    .sign(privateKey);
+}

apps/edr-passenger-api/src/modules/verifayda/utils/pkce.util.spec.ts

@@ -0,0 +1,65 @@
+import { createHash } from 'crypto';
+import {
+  base64Url,
+  generateCodeChallenge,
+  generateCodeVerifier,
+  generateState,
+} from './pkce.util';
+
+describe('pkce.util', () => {
+  describe('base64Url', () => {
+    it('strips padding and replaces + and / with - and _', () => {
+      const input = Buffer.from([0xfb, 0xff, 0xbf, 0xfe]);
+      const out = base64Url(input);
+      expect(out).not.toMatch(/[+/=]/);
+    });
+  });
+
+  describe('generateCodeVerifier', () => {
+    it('returns a base64url-safe string', () => {
+      expect(generateCodeVerifier()).toMatch(/^[A-Za-z0-9_-]+$/);
+    });
+
+    it('produces unique values across calls', () => {
+      const a = generateCodeVerifier();
+      const b = generateCodeVerifier();
+      expect(a).not.toEqual(b);
+    });
+
+    it('produces at least 43 characters (RFC 7636 minimum)', () => {
+      expect(generateCodeVerifier().length).toBeGreaterThanOrEqual(43);
+    });
+  });
+
+  describe('generateCodeChallenge', () => {
+    it('equals base64url(sha256(verifier))', () => {
+      const verifier = 'fixed-test-verifier';
+      const expected = createHash('sha256')
+        .update(verifier)
+        .digest('base64')
+        .replace(/\+/g, '-')
+        .replace(/\//g, '_')
+        .replace(/=/g, '');
+      expect(generateCodeChallenge(verifier)).toBe(expected);
+    });
+
+    it('is deterministic for the same verifier', () => {
+      const verifier = generateCodeVerifier();
+      expect(generateCodeChallenge(verifier)).toBe(generateCodeChallenge(verifier));
+    });
+
+    it('differs for different verifiers', () => {
+      expect(generateCodeChallenge('a')).not.toBe(generateCodeChallenge('b'));
+    });
+  });
+
+  describe('generateState', () => {
+    it('returns a base64url-safe string', () => {
+      expect(generateState()).toMatch(/^[A-Za-z0-9_-]+$/);
+    });
+
+    it('produces unique values across calls', () => {
+      expect(generateState()).not.toEqual(generateState());
+    });
+  });
+});

apps/edr-passenger-api/src/modules/verifayda/utils/pkce.util.ts

@@ -0,0 +1,21 @@
+import { createHash, randomBytes } from 'crypto';
+
+export function base64Url(buffer: Buffer): string {
+  return buffer
+    .toString('base64')
+    .replace(/\+/g, '-')
+    .replace(/\//g, '_')
+    .replace(/=/g, '');
+}
+
+export function generateCodeVerifier(): string {
+  return base64Url(randomBytes(64));
+}
+
+export function generateCodeChallenge(codeVerifier: string): string {
+  return base64Url(createHash('sha256').update(codeVerifier).digest());
+}
+
+export function generateState(): string {
+  return base64Url(randomBytes(32));
+}