feat(hardening): M-Hard 1-5 — crypto, auth, rate limit, fingerprints, rotation

M-Hard 1: Cryptographic Hardening
- constantTimeEqual, zeroize, randomUint32 on CryptoProvider
- Fix Math.random() → crypto.randomUint32() for registrationId
- Zero message keys and chain keys after use in ratchet.ts
- Constant-time trust comparison in MemoryStorage + SQLiteStorage
- Timing variance test catches early-exit regressions

M-Hard 2: Self-Authenticated Prekey Server
- Ed25519 signature verification on all write routes
- signPayload/verifyPayload with canonical JSON, ±5 min replay window
- Address validation (NFKC, alphanumeric + :_-.)
- Global ShadeError → HTTP status mapping
- ShadeFetchTransport signs requests when signingPrivateKey provided
- Anonymous bundle fetches still allowed (read-only)

M-Hard 3: Rate Limiting + DoS Protection
- Token bucket rate limiter with pluggable store
- Per-route limits: register 5/h/IP, fetch 60/min/IP, replenish 10/min/id
- 64KB body size limit on POST
- Retry-After header on 429 responses

M-Hard 4: Auto-replenish + Fingerprints + Session Reset
- Safety numbers (12 groups × 5 digits, Signal-style)
- ensurePreKeyStock, resetSession, acceptIdentityChange
- verifyRemoteIdentity for out-of-band comparison

M-Hard 5: Identity Rotation with Grace Period
- rotateIdentity archives old identity, generates fresh signed prekey
- RetiredIdentity storage with addRetired/getRetired/pruneRetired
- 7-day default grace period for decrypting old sessions
- pruneExpiredIdentities for cleanup

M-Hard 8: Error Hierarchy
- New error types: Network, Storage, Validation, Timeout, RateLimit,
  Configuration, Unauthorized, Replay, IdentityRotation
- All errors have stable SHADE_* codes
- errorToHttpStatus for consistent HTTP mapping
- toJSON() for network serialization

188 tests passing, zero failures.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

packages/shade-server/tests/server.test.ts

@@ -1,6 +1,10 @@
 import { describe, test, expect, beforeEach } from 'bun:test';
-import { createPrekeyServer, MemoryPrekeyStore } from '../src/index.js';
+import { createPrekeyServer, MemoryPrekeyStore, signPayload } from '../src/index.js';
 import type { PrekeyStore } from '../src/index.js';
+import { SubtleCryptoProvider } from '@shade/crypto-web';
+import { generateIdentityKeyPair } from '@shade/core';
+
+const crypto = new SubtleCryptoProvider();
 
 function b64(bytes: Uint8Array): string {
   return Buffer.from(bytes).toString('base64');
@@ -8,167 +12,164 @@ function b64(bytes: Uint8Array): string {
 
 function randBytes(n: number): Uint8Array {
   const buf = new Uint8Array(n);
-  crypto.getRandomValues(buf);
+  globalThis.crypto.getRandomValues(buf);
   return buf;
 }
 
+async function makeIdentity() {
+  return generateIdentityKeyPair(crypto);
+}
+
 describe('Shade Prekey Server', () => {
   let store: PrekeyStore;
   let app: ReturnType<typeof createPrekeyServer>;
 
   beforeEach(() => {
     store = new MemoryPrekeyStore();
-    app = createPrekeyServer({ store });
+    app = createPrekeyServer({ crypto, store, disableRateLimit: true });
   });
 
   function req(method: string, path: string, body?: any) {
     const init: RequestInit = { method, headers: { 'Content-Type': 'application/json' } };
-    if (body) init.body = JSON.stringify(body);
+    if (body !== undefined) init.body = JSON.stringify(body);
     return app.request(path, init);
   }
 
+  /** Helper: build a signed registration body for a given identity */
+  async function signedRegisterBody(identity: Awaited<ReturnType<typeof makeIdentity>>, address: string, withOTPKs = true) {
+    const body: any = {
+      address,
+      identitySigningKey: b64(identity.signingPublicKey),
+      identityDHKey: b64(identity.dhPublicKey),
+      signedPreKey: {
+        keyId: 1,
+        publicKey: b64(randBytes(32)),
+        signature: b64(randBytes(64)),
+      },
+    };
+    if (withOTPKs) {
+      body.oneTimePreKeys = [
+        { keyId: 100, publicKey: b64(randBytes(32)) },
+        { keyId: 101, publicKey: b64(randBytes(32)) },
+      ];
+    }
+    return signPayload(crypto, identity.signingPrivateKey, body);
+  }
+
   // ─── Registration ──────────────────────────────────────────
 
   describe('POST /v1/keys/register', () => {
-    test('registers identity and signed prekey', async () => {
-      const res = await req('POST', '/v1/keys/register', {
-        address: 'alice',
-        identitySigningKey: b64(randBytes(32)),
-        identityDHKey: b64(randBytes(32)),
-        signedPreKey: {
-          keyId: 1,
-          publicKey: b64(randBytes(32)),
-          signature: b64(randBytes(64)),
-        },
-      });
+    test('accepts valid signed registration', async () => {
+      const alice = await makeIdentity();
+      const body = await signedRegisterBody(alice, 'alice');
+      const res = await req('POST', '/v1/keys/register', body);
       expect(res.status).toBe(200);
-      expect(await res.json()).toEqual({ ok: true });
     });
 
-    test('registers with one-time prekeys', async () => {
+    test('rejects unsigned registration', async () => {
+      const alice = await makeIdentity();
       const res = await req('POST', '/v1/keys/register', {
         address: 'alice',
-        identitySigningKey: b64(randBytes(32)),
-        identityDHKey: b64(randBytes(32)),
-        signedPreKey: {
-          keyId: 1,
-          publicKey: b64(randBytes(32)),
-          signature: b64(randBytes(64)),
-        },
-        oneTimePreKeys: [
-          { keyId: 100, publicKey: b64(randBytes(32)) },
-          { keyId: 101, publicKey: b64(randBytes(32)) },
-          { keyId: 102, publicKey: b64(randBytes(32)) },
-        ],
+        identitySigningKey: b64(alice.signingPublicKey),
+        identityDHKey: b64(alice.dhPublicKey),
+        signedPreKey: { keyId: 1, publicKey: b64(randBytes(32)), signature: b64(randBytes(64)) },
       });
-      expect(res.status).toBe(200);
-
-      // Verify count
-      const countRes = await req('GET', '/v1/keys/count/alice');
-      expect((await countRes.json()).count).toBe(3);
-    });
-
-    test('rejects missing fields', async () => {
-      const res = await req('POST', '/v1/keys/register', { address: 'alice' });
+      // Missing signature/signedAt → validation error
       expect(res.status).toBe(400);
     });
+
+    test('rejects registration with wrong signing key', async () => {
+      const alice = await makeIdentity();
+      const bob = await makeIdentity();
+      // Sign with bob's key but claim alice's public key
+      const body: any = {
+        address: 'alice',
+        identitySigningKey: b64(alice.signingPublicKey), // mismatch
+        identityDHKey: b64(alice.dhPublicKey),
+        signedPreKey: { keyId: 1, publicKey: b64(randBytes(32)), signature: b64(randBytes(64)) },
+      };
+      const signed = await signPayload(crypto, bob.signingPrivateKey, body);
+      const res = await req('POST', '/v1/keys/register', signed);
+      expect(res.status).toBe(401);
+    });
+
+    test('rejects registration with stale signedAt', async () => {
+      const alice = await makeIdentity();
+      const body = await signedRegisterBody(alice, 'alice');
+      // Tamper with signedAt to be old
+      body.signedAt = Date.now() - 10 * 60 * 1000; // 10 minutes ago
+      const res = await req('POST', '/v1/keys/register', body);
+      expect(res.status).toBe(409); // ReplayError
+    });
+
+    test('rejects invalid address format', async () => {
+      const alice = await makeIdentity();
+      const body = await signedRegisterBody(alice, '../evil');
+      const res = await req('POST', '/v1/keys/register', body);
+      expect(res.status).toBe(400);
+    });
+
+    test('accepts registration with one-time prekeys', async () => {
+      const alice = await makeIdentity();
+      const body = await signedRegisterBody(alice, 'alice');
+      await req('POST', '/v1/keys/register', body);
+
+      const countRes = await req('GET', '/v1/keys/count/alice');
+      expect((await countRes.json()).count).toBe(2);
+    });
   });
 
-  // ─── Fetch Bundle ──────────────────────────────────────────
+  // ─── Fetch Bundle (anonymous) ──────────────────────────────
 
   describe('GET /v1/keys/bundle/:address', () => {
-    test('returns bundle with one-time prekey', async () => {
-      // Register first
-      const sigKey = b64(randBytes(32));
-      const dhKey = b64(randBytes(32));
-      const spkPub = b64(randBytes(32));
-      const spkSig = b64(randBytes(64));
-      const otpkPub = b64(randBytes(32));
-
-      await req('POST', '/v1/keys/register', {
-        address: 'bob',
-        identitySigningKey: sigKey,
-        identityDHKey: dhKey,
-        signedPreKey: { keyId: 1, publicKey: spkPub, signature: spkSig },
-        oneTimePreKeys: [{ keyId: 100, publicKey: otpkPub }],
-      });
+    test('returns bundle for registered address', async () => {
+      const bob = await makeIdentity();
+      const body = await signedRegisterBody(bob, 'bob');
+      await req('POST', '/v1/keys/register', body);
 
       const res = await req('GET', '/v1/keys/bundle/bob');
       expect(res.status).toBe(200);
 
       const bundle = await res.json();
-      expect(bundle.identitySigningKey).toBe(sigKey);
-      expect(bundle.identityDHKey).toBe(dhKey);
+      expect(bundle.identitySigningKey).toBe(b64(bob.signingPublicKey));
+      expect(bundle.identityDHKey).toBe(b64(bob.dhPublicKey));
       expect(bundle.signedPreKey.keyId).toBe(1);
-      expect(bundle.signedPreKey.publicKey).toBe(spkPub);
-      expect(bundle.signedPreKey.signature).toBe(spkSig);
       expect(bundle.oneTimePreKey.keyId).toBe(100);
-      expect(bundle.oneTimePreKey.publicKey).toBe(otpkPub);
     });
 
-    test('returns bundle without one-time prekey when depleted', async () => {
-      await req('POST', '/v1/keys/register', {
-        address: 'bob',
-        identitySigningKey: b64(randBytes(32)),
-        identityDHKey: b64(randBytes(32)),
-        signedPreKey: { keyId: 1, publicKey: b64(randBytes(32)), signature: b64(randBytes(64)) },
-      });
+    test('consumes one-time prekey on each fetch (FIFO)', async () => {
+      const bob = await makeIdentity();
+      await req('POST', '/v1/keys/register', await signedRegisterBody(bob, 'bob'));
 
-      const res = await req('GET', '/v1/keys/bundle/bob');
-      expect(res.status).toBe(200);
-
-      const bundle = await res.json();
-      expect(bundle.oneTimePreKey).toBeUndefined();
-    });
-
-    test('consumes one-time prekeys on each fetch', async () => {
-      await req('POST', '/v1/keys/register', {
-        address: 'bob',
-        identitySigningKey: b64(randBytes(32)),
-        identityDHKey: b64(randBytes(32)),
-        signedPreKey: { keyId: 1, publicKey: b64(randBytes(32)), signature: b64(randBytes(64)) },
-        oneTimePreKeys: [
-          { keyId: 100, publicKey: b64(randBytes(32)) },
-          { keyId: 101, publicKey: b64(randBytes(32)) },
-        ],
-      });
-
-      // First fetch consumes key 100
       const res1 = await req('GET', '/v1/keys/bundle/bob');
       expect((await res1.json()).oneTimePreKey.keyId).toBe(100);
 
-      // Second fetch consumes key 101
       const res2 = await req('GET', '/v1/keys/bundle/bob');
       expect((await res2.json()).oneTimePreKey.keyId).toBe(101);
 
-      // Third fetch has none left
       const res3 = await req('GET', '/v1/keys/bundle/bob');
       expect((await res3.json()).oneTimePreKey).toBeUndefined();
-
-      // Count should be 0
-      const countRes = await req('GET', '/v1/keys/count/bob');
-      expect((await countRes.json()).count).toBe(0);
     });
 
     test('404 for unknown address', async () => {
       const res = await req('GET', '/v1/keys/bundle/nobody');
       expect(res.status).toBe(404);
     });
+
+    test('rejects invalid address in URL', async () => {
+      const res = await req('GET', '/v1/keys/bundle/..evil');
+      expect(res.status).toBe(400);
+    });
   });
 
-  // ─── Replenish ─────────────────────────────────────────────
+  // ─── Replenish (signed) ────────────────────────────────────
 
   describe('POST /v1/keys/replenish', () => {
-    test('adds more one-time prekeys', async () => {
-      await req('POST', '/v1/keys/register', {
-        address: 'bob',
-        identitySigningKey: b64(randBytes(32)),
-        identityDHKey: b64(randBytes(32)),
-        signedPreKey: { keyId: 1, publicKey: b64(randBytes(32)), signature: b64(randBytes(64)) },
-        oneTimePreKeys: [{ keyId: 100, publicKey: b64(randBytes(32)) }],
-      });
+    test('accepts signed replenishment from registered identity', async () => {
+      const bob = await makeIdentity();
+      await req('POST', '/v1/keys/register', await signedRegisterBody(bob, 'bob'));
 
-      const res = await req('POST', '/v1/keys/replenish', {
+      const replenishBody = await signPayload(crypto, bob.signingPrivateKey, {
         address: 'bob',
         oneTimePreKeys: [
           { keyId: 200, publicKey: b64(randBytes(32)) },
@@ -176,52 +177,83 @@ describe('Shade Prekey Server', () => {
         ],
       });
 
+      const res = await req('POST', '/v1/keys/replenish', replenishBody);
       expect(res.status).toBe(200);
       const body = await res.json();
-      expect(body.remaining).toBe(3); // 1 original + 2 new
+      expect(body.remaining).toBe(4); // 2 original + 2 new
+    });
+
+    test('rejects replenishment signed by wrong identity', async () => {
+      const bob = await makeIdentity();
+      const eve = await makeIdentity();
+      await req('POST', '/v1/keys/register', await signedRegisterBody(bob, 'bob'));
+
+      const evilBody = await signPayload(crypto, eve.signingPrivateKey, {
+        address: 'bob',
+        oneTimePreKeys: [{ keyId: 200, publicKey: b64(randBytes(32)) }],
+      });
+
+      const res = await req('POST', '/v1/keys/replenish', evilBody);
+      expect(res.status).toBe(401);
+    });
+
+    test('rejects replenishment for unknown address', async () => {
+      const bob = await makeIdentity();
+      const body = await signPayload(crypto, bob.signingPrivateKey, {
+        address: 'nobody',
+        oneTimePreKeys: [{ keyId: 200, publicKey: b64(randBytes(32)) }],
+      });
+      const res = await req('POST', '/v1/keys/replenish', body);
+      expect(res.status).toBe(404);
     });
   });
 
-  // ─── Delete ────────────────────────────────────────────────
+  // ─── Delete (signed) ───────────────────────────────────────
 
   describe('DELETE /v1/keys/:address', () => {
-    test('removes all keys for an address', async () => {
-      await req('POST', '/v1/keys/register', {
-        address: 'bob',
-        identitySigningKey: b64(randBytes(32)),
-        identityDHKey: b64(randBytes(32)),
-        signedPreKey: { keyId: 1, publicKey: b64(randBytes(32)), signature: b64(randBytes(64)) },
-        oneTimePreKeys: [{ keyId: 100, publicKey: b64(randBytes(32)) }],
-      });
+    test('accepts signed delete from registered identity', async () => {
+      const bob = await makeIdentity();
+      await req('POST', '/v1/keys/register', await signedRegisterBody(bob, 'bob'));
 
-      const delRes = await req('DELETE', '/v1/keys/bob');
-      expect(delRes.status).toBe(200);
+      const delBody = await signPayload(crypto, bob.signingPrivateKey, { address: 'bob' });
+      const res = await req('DELETE', '/v1/keys/bob', delBody);
+      expect(res.status).toBe(200);
 
       // Should be gone
       const bundleRes = await req('GET', '/v1/keys/bundle/bob');
       expect(bundleRes.status).toBe(404);
+    });
 
-      const countRes = await req('GET', '/v1/keys/count/bob');
-      expect((await countRes.json()).count).toBe(0);
+    test('rejects delete signed by wrong identity', async () => {
+      const bob = await makeIdentity();
+      const eve = await makeIdentity();
+      await req('POST', '/v1/keys/register', await signedRegisterBody(bob, 'bob'));
+
+      const evilBody = await signPayload(crypto, eve.signingPrivateKey, { address: 'bob' });
+      const res = await req('DELETE', '/v1/keys/bob', evilBody);
+      expect(res.status).toBe(401);
+
+      // Should still exist
+      const bundleRes = await req('GET', '/v1/keys/bundle/bob');
+      expect(bundleRes.status).toBe(200);
     });
   });
 
-  // ─── Multiple Addresses ────────────────────────────────────
+  // ─── Multi-address isolation ───────────────────────────────
 
   describe('multi-address isolation', () => {
     test('different addresses are independent', async () => {
-      for (const addr of ['alice', 'bob', 'charlie']) {
-        await req('POST', '/v1/keys/register', {
-          address: addr,
-          identitySigningKey: b64(randBytes(32)),
-          identityDHKey: b64(randBytes(32)),
-          signedPreKey: { keyId: 1, publicKey: b64(randBytes(32)), signature: b64(randBytes(64)) },
-          oneTimePreKeys: [{ keyId: 1, publicKey: b64(randBytes(32)) }],
-        });
-      }
+      const alice = await makeIdentity();
+      const bob = await makeIdentity();
+      const charlie = await makeIdentity();
 
-      // Delete bob, others remain
-      await req('DELETE', '/v1/keys/bob');
+      await req('POST', '/v1/keys/register', await signedRegisterBody(alice, 'alice'));
+      await req('POST', '/v1/keys/register', await signedRegisterBody(bob, 'bob'));
+      await req('POST', '/v1/keys/register', await signedRegisterBody(charlie, 'charlie'));
+
+      // Delete bob with his own signature
+      const delBody = await signPayload(crypto, bob.signingPrivateKey, { address: 'bob' });
+      await req('DELETE', '/v1/keys/bob', delBody);
 
       expect((await req('GET', '/v1/keys/bundle/alice')).status).toBe(200);
       expect((await req('GET', '/v1/keys/bundle/bob')).status).toBe(404);