Implement Signal Protocol

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2025-11-19 16:01:25 +03:00
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parent 8bda2220c6
commit d4b1e261d7
19 changed files with 1352 additions and 444 deletions
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/**
* Signal Protocol service wrapper
* Provides high-level API for encrypting/decrypting messages using Signal Protocol
*/
import {
SessionBuilder,
SessionCipher,
KeyHelper,
SignalProtocolAddress,
type DeviceType
} from "@privacyresearch/libsignal-protocol-typescript";
import { SignalProtocolStorage } from "./signalStorage";
import { b64, ub64 } from "../utils";
// Helper to ensure we get a proper ArrayBuffer (not SharedArrayBuffer)
function toArrayBuffer(buffer: ArrayBuffer | SharedArrayBuffer): ArrayBuffer {
if (buffer instanceof ArrayBuffer) return buffer;
// Convert SharedArrayBuffer to ArrayBuffer by copying
const view = new Uint8Array(buffer);
const copy = new Uint8Array(view.length);
copy.set(view);
return copy.buffer;
}
export interface PreKeyBundleData {
registrationId: number;
identityKey: string; // base64
signedPreKey: {
keyId: number;
publicKey: string; // base64
signature: string; // base64
};
preKey?: {
keyId: number;
publicKey: string; // base64
};
}
export class SignalProtocolService {
private storage: SignalProtocolStorage;
constructor(userId: string) {
this.storage = new SignalProtocolStorage(userId);
}
/**
* Initialize Signal Protocol for this user
* Generates identity keys, registration ID, and prekeys if they don't exist
*/
async initialize(): Promise<void> {
// Check if already initialized
const existingIdentity = await this.storage.getIdentityKeyPair();
if (existingIdentity) {
return; // Already initialized
}
// Generate identity key pair
const identityKeyPair = await KeyHelper.generateIdentityKeyPair();
await this.storage.saveIdentityKeyPair(identityKeyPair);
// Generate registration ID
const registrationId = KeyHelper.generateRegistrationId();
await this.storage.saveLocalRegistrationId(registrationId);
// Generate signed prekey
const signedPreKeyId = 1;
const signedPreKey = await KeyHelper.generateSignedPreKey(identityKeyPair, signedPreKeyId);
await this.storage.storeSignedPreKey(signedPreKeyId, signedPreKey.keyPair);
// Store signature separately (we'll need it for the bundle)
// For now, we'll regenerate it when needed since storage doesn't store signatures
// Generate prekeys (typically 100 prekeys)
const preKeyCount = 100;
for (let i = 1; i <= preKeyCount; i++) {
const preKey = await KeyHelper.generatePreKey(i);
await this.storage.storePreKey(i, preKey.keyPair);
}
}
/**
* Get prekey bundle for this user to share with others
*/
async getPreKeyBundle(): Promise<PreKeyBundleData> {
const identityKeyPair = await this.storage.getIdentityKeyPair();
if (!identityKeyPair) {
throw new Error("Signal Protocol not initialized");
}
const registrationId = await this.storage.getLocalRegistrationId();
if (!registrationId) {
throw new Error("Registration ID not found");
}
const signedPreKey = await this.storage.loadSignedPreKey(1);
if (!signedPreKey) {
throw new Error("Signed prekey not found");
}
// Regenerate signed prekey to get signature (since storage doesn't store it)
// In production, you'd store the signature separately
const signedPreKeyWithSig = await KeyHelper.generateSignedPreKey(identityKeyPair, 1);
await this.storage.storeSignedPreKey(1, signedPreKeyWithSig.keyPair);
// Get a prekey to include
const preKey = await this.storage.loadPreKey(1);
if (!preKey) {
throw new Error("No prekeys available");
}
return {
registrationId: registrationId,
identityKey: b64(new Uint8Array(identityKeyPair.pubKey)),
signedPreKey: {
keyId: 1,
publicKey: b64(new Uint8Array(signedPreKey.pubKey)),
signature: b64(new Uint8Array(signedPreKeyWithSig.signature))
},
preKey: {
keyId: 1,
publicKey: b64(new Uint8Array(preKey.pubKey))
}
};
}
/**
* Process a prekey bundle from another user and establish a session
*/
async processPreKeyBundle(recipientId: number, bundle: PreKeyBundleData): Promise<void> {
const address = new SignalProtocolAddress(recipientId.toString(), 1);
const identityKeyBuf = ub64(bundle.identityKey);
const signedPreKeyPubBuf = ub64(bundle.signedPreKey.publicKey);
const signedPreKeySigBuf = ub64(bundle.signedPreKey.signature);
const deviceBundle: DeviceType = {
identityKey: toArrayBuffer(identityKeyBuf.buffer.slice(identityKeyBuf.byteOffset, identityKeyBuf.byteOffset + identityKeyBuf.byteLength)),
signedPreKey: {
keyId: bundle.signedPreKey.keyId,
publicKey: toArrayBuffer(signedPreKeyPubBuf.buffer.slice(signedPreKeyPubBuf.byteOffset, signedPreKeyPubBuf.byteOffset + signedPreKeyPubBuf.byteLength)),
signature: toArrayBuffer(signedPreKeySigBuf.buffer.slice(signedPreKeySigBuf.byteOffset, signedPreKeySigBuf.byteOffset + signedPreKeySigBuf.byteLength))
},
preKey: bundle.preKey ? {
keyId: bundle.preKey.keyId,
publicKey: (() => {
const preKeyBuf = ub64(bundle.preKey!.publicKey);
return toArrayBuffer(preKeyBuf.buffer.slice(preKeyBuf.byteOffset, preKeyBuf.byteOffset + preKeyBuf.byteLength));
})()
} : undefined,
registrationId: bundle.registrationId
};
const sessionBuilder = new SessionBuilder(this.storage, address);
await sessionBuilder.processPreKey(deviceBundle);
}
/**
* Encrypt a message for a recipient
*/
async encryptMessage(recipientId: number, plaintext: string): Promise<{ type: number; body: string }> {
const address = new SignalProtocolAddress(recipientId.toString(), 1);
const sessionCipher = new SessionCipher(this.storage, address);
const plaintextBuffer = toArrayBuffer(new TextEncoder().encode(plaintext).buffer);
const { type, body } = await sessionCipher.encrypt(plaintextBuffer);
if (!body) {
throw new Error("Encryption failed: no body in ciphertext");
}
// ciphertext.body is a base64 string, but we need to convert it properly
// According to the library, body is a serialized protobuf message as base64 string
return { type, body };
}
/**
* Decrypt a message from a sender
*/
async decryptMessage(senderId: number, ciphertext: { type: number; body: string }): Promise<string> {
const address = new SignalProtocolAddress(senderId.toString(), 1);
const sessionCipher = new SessionCipher(this.storage, address);
// Handle both PreKeyWhisperMessage (type 3) and WhisperMessage (type 1)
const { buffer, byteOffset, byteLength } = ub64(ciphertext.body);
const bodyBuffer = toArrayBuffer(buffer.slice(byteOffset, byteOffset + byteLength));
let plaintextBytes: ArrayBuffer;
if (ciphertext.type === 3) {
// PreKeyWhisperMessage
plaintextBytes = await sessionCipher.decryptPreKeyWhisperMessage(bodyBuffer);
} else {
// WhisperMessage
plaintextBytes = await sessionCipher.decryptWhisperMessage(bodyBuffer);
}
return new TextDecoder().decode(plaintextBytes);
}
/**
* Check if a session exists for a recipient
*/
async hasSession(recipientId: number): Promise<boolean> {
const address = new SignalProtocolAddress(recipientId.toString(), 1);
const sessionCipher = new SessionCipher(this.storage, address);
return await sessionCipher.hasOpenSession();
}
}
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/**
* IndexedDB storage implementation for Signal Protocol
* Stores identity keys, prekeys, signed prekeys, and session states
*/
import type { StorageType, KeyPairType, Direction } from "@privacyresearch/libsignal-protocol-typescript";
const DB_NAME = "signal_protocol_db";
const DB_VERSION = 1;
interface SignalDB {
identityKeys: IDBObjectStore;
preKeys: IDBObjectStore;
signedPreKeys: IDBObjectStore;
sessions: IDBObjectStore;
registrationId: IDBObjectStore;
}
let dbPromise: Promise<IDBDatabase> | null = null;
function openDB(): Promise<IDBDatabase> {
if (dbPromise) return dbPromise;
dbPromise = new Promise((resolve, reject) => {
const request = indexedDB.open(DB_NAME, DB_VERSION);
request.onerror = () => reject(request.error);
request.onsuccess = () => resolve(request.result);
request.onupgradeneeded = (event) => {
const db = (event.target as IDBOpenDBRequest).result;
// Identity keys store: key = userId, value = { publicKey, privateKey }
if (!db.objectStoreNames.contains("identityKeys")) {
db.createObjectStore("identityKeys", { keyPath: "userId" });
}
// Prekeys store: key = userId + preKeyId, value = { userId, preKeyId, publicKey, privateKey }
if (!db.objectStoreNames.contains("preKeys")) {
const preKeysStore = db.createObjectStore("preKeys", { keyPath: ["userId", "preKeyId"] });
preKeysStore.createIndex("userId", "userId", { unique: false });
}
// Signed prekeys store: key = userId, value = { userId, keyId, publicKey, privateKey, signature }
if (!db.objectStoreNames.contains("signedPreKeys")) {
db.createObjectStore("signedPreKeys", { keyPath: "userId" });
}
// Sessions store: key = userId + deviceId, value = { userId, deviceId, record }
if (!db.objectStoreNames.contains("sessions")) {
const sessionsStore = db.createObjectStore("sessions", { keyPath: ["userId", "deviceId"] });
sessionsStore.createIndex("userId", "userId", { unique: false });
}
// Registration ID store: key = userId, value = { userId, registrationId }
if (!db.objectStoreNames.contains("registrationId")) {
db.createObjectStore("registrationId", { keyPath: "userId" });
}
};
});
return dbPromise;
}
async function getStore(storeName: keyof SignalDB, mode: IDBTransactionMode = "readonly"): Promise<IDBObjectStore> {
const db = await openDB();
const tx = db.transaction([storeName], mode);
return tx.objectStore(storeName);
}
// Helper to convert Uint8Array to ArrayBuffer
function toArrayBuffer(u8: Uint8Array | ArrayBuffer): ArrayBuffer {
if (u8 instanceof ArrayBuffer) return u8;
return u8.buffer.slice(u8.byteOffset, u8.byteOffset + u8.byteLength);
}
// Helper to convert ArrayBuffer to Uint8Array
function toUint8Array(ab: ArrayBuffer | Uint8Array): Uint8Array {
if (ab instanceof Uint8Array) return ab;
return new Uint8Array(ab);
}
export class SignalProtocolStorage implements StorageType {
private userId: string;
constructor(userId: string) {
this.userId = userId;
}
// Identity Key Management
async getIdentityKeyPair(): Promise<KeyPairType | undefined> {
const store = await getStore("identityKeys");
const result = await new Promise<{ publicKey: ArrayBuffer; privateKey: ArrayBuffer } | undefined>((resolve, reject) => {
const request = store.get(this.userId);
request.onsuccess = () => {
const data = request.result;
if (!data) {
resolve(undefined);
return;
}
resolve({
pubKey: toArrayBuffer(data.publicKey),
privKey: toArrayBuffer(data.privateKey)
});
};
request.onerror = () => reject(request.error);
});
return result;
}
async getLocalRegistrationId(): Promise<number | undefined> {
const store = await getStore("registrationId");
const result = await new Promise<{ registrationId: number } | undefined>((resolve, reject) => {
const request = store.get(this.userId);
request.onsuccess = () => {
const data = request.result;
resolve(data ? { registrationId: data.registrationId } : undefined);
};
request.onerror = () => reject(request.error);
});
return result?.registrationId;
}
async isTrustedIdentity(identifier: string, identityKey: ArrayBuffer, direction: Direction): Promise<boolean> {
// For now, always trust (can be enhanced with key verification)
// In production, you'd check against previously stored identity keys
return true;
}
async saveIdentity(encodedAddress: string, publicKey: ArrayBuffer, nonblockingApproval?: boolean): Promise<boolean> {
// Store other users' identity keys if needed
// For now, we trust all identities
return true;
}
// Helper methods for initialization (not part of StorageType interface)
async saveIdentityKeyPair(keyPair: KeyPairType): Promise<void> {
const store = await getStore("identityKeys", "readwrite");
await new Promise<void>((resolve, reject) => {
const request = store.put({
userId: this.userId,
publicKey: toUint8Array(keyPair.pubKey),
privateKey: toUint8Array(keyPair.privKey)
});
request.onsuccess = () => resolve();
request.onerror = () => reject(request.error);
});
}
async saveLocalRegistrationId(registrationId: number): Promise<void> {
const store = await getStore("registrationId", "readwrite");
await new Promise<void>((resolve, reject) => {
const request = store.put({
userId: this.userId,
registrationId: registrationId
});
request.onsuccess = () => resolve();
request.onerror = () => reject(request.error);
});
}
// PreKey Management
async loadPreKey(encodedAddress: string | number): Promise<KeyPairType | undefined> {
const preKeyId = typeof encodedAddress === "number" ? encodedAddress : parseInt(encodedAddress, 10);
const store = await getStore("preKeys");
const result = await new Promise<{ publicKey: ArrayBuffer; privateKey: ArrayBuffer } | undefined>((resolve, reject) => {
const request = store.get([this.userId, preKeyId]);
request.onsuccess = () => {
const data = request.result;
if (!data) {
resolve(undefined);
return;
}
resolve({
pubKey: toArrayBuffer(data.publicKey),
privKey: toArrayBuffer(data.privateKey)
});
};
request.onerror = () => reject(request.error);
});
return result;
}
async storePreKey(keyId: number | string, keyPair: KeyPairType): Promise<void> {
const preKeyId = typeof keyId === "number" ? keyId : parseInt(keyId, 10);
const store = await getStore("preKeys", "readwrite");
await new Promise<void>((resolve, reject) => {
const request = store.put({
userId: this.userId,
preKeyId: preKeyId,
publicKey: toUint8Array(keyPair.pubKey),
privateKey: toUint8Array(keyPair.privKey)
});
request.onsuccess = () => resolve();
request.onerror = () => reject(request.error);
});
}
async removePreKey(keyId: number | string): Promise<void> {
const preKeyId = typeof keyId === "number" ? keyId : parseInt(keyId, 10);
const store = await getStore("preKeys", "readwrite");
await new Promise<void>((resolve, reject) => {
const request = store.delete([this.userId, preKeyId]);
request.onsuccess = () => resolve();
request.onerror = () => reject(request.error);
});
}
// Signed PreKey Management
async loadSignedPreKey(keyId: number | string): Promise<KeyPairType | undefined> {
const signedPreKeyId = typeof keyId === "number" ? keyId : parseInt(keyId, 10);
const store = await getStore("signedPreKeys");
const result = await new Promise<{ publicKey: ArrayBuffer; privateKey: ArrayBuffer; keyId: number } | undefined>((resolve, reject) => {
const request = store.get(this.userId);
request.onsuccess = () => {
const data = request.result;
if (!data || data.keyId !== signedPreKeyId) {
resolve(undefined);
return;
}
resolve({
pubKey: toArrayBuffer(data.publicKey),
privKey: toArrayBuffer(data.privateKey)
});
};
request.onerror = () => reject(request.error);
});
return result;
}
async storeSignedPreKey(keyId: number | string, keyPair: KeyPairType): Promise<void> {
const signedPreKeyId = typeof keyId === "number" ? keyId : parseInt(keyId, 10);
const store = await getStore("signedPreKeys", "readwrite");
await new Promise<void>((resolve, reject) => {
const request = store.put({
userId: this.userId,
keyId: signedPreKeyId,
publicKey: toUint8Array(keyPair.pubKey),
privateKey: toUint8Array(keyPair.privKey)
});
request.onsuccess = () => resolve();
request.onerror = () => reject(request.error);
});
}
async removeSignedPreKey(keyId: number | string): Promise<void> {
const store = await getStore("signedPreKeys", "readwrite");
await new Promise<void>((resolve, reject) => {
const request = store.delete(this.userId);
request.onsuccess = () => resolve();
request.onerror = () => reject(request.error);
});
}
// Session Management
async loadSession(encodedAddress: string): Promise<string | undefined> {
// encodedAddress format: "userId.deviceId"
const parts = encodedAddress.split(".");
const deviceId = parts.length > 1 ? parts[1] : encodedAddress;
const store = await getStore("sessions");
const result = await new Promise<{ record: string } | undefined>((resolve, reject) => {
const request = store.get([this.userId, deviceId]);
request.onsuccess = () => {
const data = request.result;
resolve(data ? data.record : undefined);
};
request.onerror = () => reject(request.error);
});
return result;
}
async storeSession(encodedAddress: string, record: string): Promise<void> {
// encodedAddress format: "userId.deviceId"
const parts = encodedAddress.split(".");
const deviceId = parts.length > 1 ? parts[1] : encodedAddress;
const store = await getStore("sessions", "readwrite");
await new Promise<void>((resolve, reject) => {
const request = store.put({
userId: this.userId,
deviceId: deviceId,
record: record
});
request.onsuccess = () => resolve();
request.onerror = () => reject(request.error);
});
}
}