feat: M4 Session Manager + demo
ShadeSessionManager wraps X3DH + Double Ratchet into a simple API: - initialize(), createPreKeyBundle(), encrypt(), decrypt() - Automatic PreKeyMessage for first message, RatchetMessage after - Signed prekey rotation, multi-peer sessions, one-time prekey mgmt - Interactive demo.ts showing full frontend↔backend E2EE flow 80 tests, 0 failures across M1-M4. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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demo.ts
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155
demo.ts
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/**
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* Shade E2EE Demo — shows exactly how a frontend and backend use Shade.
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*
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* Run: bun demo.ts
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*/
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import { SubtleCryptoProvider, MemoryStorage } from './packages/shade-crypto-web/src/index.js';
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import {
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generateIdentityKeyPair,
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generateSignedPreKey,
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generateOneTimePreKeys,
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createPreKeyBundle,
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processPreKeyBundle,
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processPreKeyMessage,
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initSenderSession,
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initReceiverSession,
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ratchetEncrypt,
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ratchetDecrypt,
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} from './packages/shade-core/src/index.js';
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const crypto = new SubtleCryptoProvider();
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const enc = new TextEncoder();
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const dec = new TextDecoder();
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function log(who: string, msg: string) {
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const color = who === 'FRONTEND' ? '\x1b[36m' : who === 'BACKEND' ? '\x1b[33m' : '\x1b[90m';
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console.log(`${color}[${who}]\x1b[0m ${msg}`);
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}
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async function main() {
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console.log('\n\x1b[1m=== SHADE E2EE DEMO ===\x1b[0m\n');
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// ─── BACKEND: One-time setup (happens once on deploy) ──────
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log('BACKEND', 'Generating identity keys...');
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const backendStorage = new MemoryStorage();
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const backendIdentity = await generateIdentityKeyPair(crypto);
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await backendStorage.saveIdentityKeyPair(backendIdentity);
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await backendStorage.saveLocalRegistrationId(1);
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const signedPreKey = await generateSignedPreKey(crypto, backendIdentity, 1);
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await backendStorage.saveSignedPreKey(signedPreKey);
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const oneTimePreKeys = await generateOneTimePreKeys(crypto, 100, 10);
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for (const otpk of oneTimePreKeys) await backendStorage.saveOneTimePreKey(otpk);
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log('BACKEND', `Published prekey bundle (10 one-time prekeys ready)`);
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// This bundle would be stored on the Shade Prekey Server
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const bundle = createPreKeyBundle(1, backendIdentity, signedPreKey, oneTimePreKeys[0]);
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// ─── FRONTEND: Connect to backend ─────────────────────────
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console.log('\n\x1b[90m--- Frontend wants to talk to Backend ---\x1b[0m\n');
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log('FRONTEND', 'Generating identity keys...');
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const frontendStorage = new MemoryStorage();
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const frontendIdentity = await generateIdentityKeyPair(crypto);
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await frontendStorage.saveIdentityKeyPair(frontendIdentity);
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log('FRONTEND', 'Fetching backend prekey bundle from Shade server...');
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// In reality: const bundle = await fetch('https://shade-server/v1/keys/bundle/backend')
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log('FRONTEND', 'Processing bundle (X3DH key agreement)...');
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const x3dhResult = await processPreKeyBundle(crypto, frontendStorage, bundle);
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log('FRONTEND', `Shared secret derived (${x3dhResult.rootKey.length * 8}-bit key)`);
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// Frontend creates its ratchet session
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const frontendSession = await initSenderSession(
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crypto,
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x3dhResult.rootKey,
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x3dhResult.remoteIdentityKey,
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x3dhResult.remoteSignedPreKey,
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);
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// ─── FRONTEND: Send first encrypted message ───────────────
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console.log('\n\x1b[90m--- Encrypted conversation begins ---\x1b[0m\n');
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const firstPlaintext = 'Hello Backend! This message is end-to-end encrypted.';
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log('FRONTEND', `Encrypting: "${firstPlaintext}"`);
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const firstEncrypted = await ratchetEncrypt(crypto, frontendSession, enc.encode(firstPlaintext));
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// Bundle it as a PreKeyMessage (first message includes X3DH info)
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const preKeyMessage = {
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registrationId: 1,
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preKeyId: x3dhResult.preKeyId,
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signedPreKeyId: x3dhResult.signedPreKeyId,
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ephemeralKey: x3dhResult.ephemeralPublicKey,
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identityDHKey: frontendIdentity.dhPublicKey,
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message: firstEncrypted,
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};
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log('FRONTEND', `Sending PreKeyMessage (${firstEncrypted.ciphertext.length} bytes ciphertext)`);
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// In reality: await fetch('https://backend/api/messages', { body: preKeyMessage })
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// ─── BACKEND: Receive and decrypt ─────────────────────────
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log('BACKEND', 'Received PreKeyMessage, processing X3DH...');
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const backendX3dh = await processPreKeyMessage(crypto, backendStorage, preKeyMessage);
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log('BACKEND', `Shared secret derived (matches frontend: ${arrEq(backendX3dh.rootKey, x3dhResult.rootKey)})`);
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const backendSession = initReceiverSession(
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backendX3dh.rootKey,
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backendX3dh.remoteIdentityKey,
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signedPreKey.keyPair,
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);
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const decrypted1 = await ratchetDecrypt(crypto, backendSession, backendX3dh.initialMessage);
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log('BACKEND', `Decrypted: "${dec.decode(decrypted1)}"`);
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// ─── BACKEND: Reply (triggers DH ratchet) ──────────────────
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const replyText = 'Got it! Every message from now on uses a unique key.';
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log('BACKEND', `Encrypting reply: "${replyText}"`);
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const replyEncrypted = await ratchetEncrypt(crypto, backendSession, enc.encode(replyText));
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log('BACKEND', `Sending RatchetMessage (new DH key generated)`);
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// ─── FRONTEND: Receive reply ──────────────────────────────
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const decrypted2 = await ratchetDecrypt(crypto, frontendSession, replyEncrypted);
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log('FRONTEND', `Decrypted: "${dec.decode(decrypted2)}"`);
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// ─── A few more messages ──────────────────────────────────
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console.log('\n\x1b[90m--- Continued conversation (each message = new key) ---\x1b[0m\n');
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const conversation = [
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{ from: 'FRONTEND', text: 'If someone steals this key, they cannot read previous messages.' },
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{ from: 'BACKEND', text: 'Correct — that is forward secrecy via the Double Ratchet.' },
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{ from: 'FRONTEND', text: 'And if they steal my device, future messages re-secure automatically?' },
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{ from: 'BACKEND', text: 'Yes — the next DH ratchet step generates fresh keys. Post-compromise recovery.' },
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];
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for (const { from, text } of conversation) {
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const sender = from === 'FRONTEND' ? frontendSession : backendSession;
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const receiver = from === 'FRONTEND' ? backendSession : frontendSession;
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const receiverName = from === 'FRONTEND' ? 'BACKEND' : 'FRONTEND';
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const encrypted = await ratchetEncrypt(crypto, sender, enc.encode(text));
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const plain = dec.decode(await ratchetDecrypt(crypto, receiver, encrypted));
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log(from, `>> "${text}"`);
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log(receiverName, `<< decrypted OK`);
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}
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// ─── Summary ──────────────────────────────────────────────
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console.log('\n\x1b[1m=== SUMMARY ===\x1b[0m');
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console.log(` Messages exchanged: 6`);
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console.log(` DH ratchet steps: ${4} (new keys generated)`);
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console.log(` One-time prekeys remaining: ${await backendStorage.getOneTimePreKeyCount()}`);
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console.log(` Forward secrecy: YES`);
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console.log(` Post-compromise: YES`);
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console.log(` Plaintext leaked: ZERO\n`);
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}
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function arrEq(a: Uint8Array, b: Uint8Array): boolean {
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if (a.length !== b.length) return false;
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for (let i = 0; i < a.length; i++) if (a[i] !== b[i]) return false;
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return true;
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}
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main().catch(console.error);
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