Support for translating Desktop sessions to libsignal-client sessions
This commit is contained in:
Scott Nonnenberg
Josh Perez
parent
44dfd28017
commit
c73e35b1b6
7 changed files with 1513 additions and 73 deletions
409
ts/util/sessionTranslation.ts
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409
ts/util/sessionTranslation.ts
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// Copyright 2021 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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import { get, isFinite, isInteger, isString } from 'lodash';
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import { HKDF } from 'libsignal-client';
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import { signal } from '../protobuf/compiled';
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import {
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bytesFromString,
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fromEncodedBinaryToArrayBuffer,
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typedArrayToArrayBuffer,
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} from '../Crypto';
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const { RecordStructure, SessionStructure } = signal.proto.storage;
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const { Chain } = SessionStructure;
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type KeyPairType = {
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privKey?: string;
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pubKey?: string;
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};
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type OldRatchetType = {
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added?: number;
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ephemeralKey?: string;
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};
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type SessionType = {
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registrationId?: number;
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currentRatchet?: {
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rootKey?: string;
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lastRemoteEphemeralKey?: string;
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previousCounter?: number;
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ephemeralKeyPair?: KeyPairType;
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};
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indexInfo?: {
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remoteIdentityKey?: string;
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closed?: number;
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baseKey?: string;
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baseKeyType?: number;
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};
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pendingPreKey?: {
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baseKey?: string;
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signedPreKeyId?: number;
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// The first two are required; this one is optional
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preKeyId?: number;
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};
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oldRatchetList?: Array<OldRatchetType>;
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// Note: ChainTypes are stored here, keyed by their baseKey. Typescript
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/// doesn't allow that kind of combination definition (known keys and
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// indexer), so we force session to `any` below whenever we access it like
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// `session[baseKey]`.
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};
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type MessageKeyGroup = {
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[key: string]: string;
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};
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type ChainType = {
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messageKeys?: MessageKeyGroup;
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chainKey?: {
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counter?: number;
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key?: string;
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};
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chainType: number;
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};
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type SessionListType = {
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[key: string]: SessionType;
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};
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type SessionRecordType = {
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sessions?: SessionListType;
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version?: 'v1';
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};
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export type LocalUserDataType = {
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identityKeyPublic: ArrayBuffer;
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registrationId: number;
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};
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export function sessionStructureToArrayBuffer(
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recordStructure: signal.proto.storage.RecordStructure
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): ArrayBuffer {
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return typedArrayToArrayBuffer(
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signal.proto.storage.RecordStructure.encode(recordStructure).finish()
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);
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}
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export function sessionRecordToProtobuf(
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record: SessionRecordType,
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ourData: LocalUserDataType
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): signal.proto.storage.RecordStructure {
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const proto = new RecordStructure();
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proto.previousSessions = [];
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const sessionGroup = record.sessions || {};
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const sessions = Object.values(sessionGroup);
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const first = sessions.find(session => {
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return session?.indexInfo?.closed === -1;
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});
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if (first) {
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proto.currentSession = toProtobufSession(first, ourData);
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}
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sessions.sort((left, right) => {
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// Descending - we want recently-closed sessions to be first
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return (right?.indexInfo?.closed || 0) - (left?.indexInfo?.closed || 0);
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});
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const onlyClosed = sessions.filter(
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session => session?.indexInfo?.closed !== -1
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);
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if (onlyClosed.length < sessions.length - 1) {
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throw new Error('toProtobuf: More than one open session!');
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}
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proto.previousSessions = [];
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onlyClosed.forEach(session => {
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proto.previousSessions.push(toProtobufSession(session, ourData));
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});
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if (!proto.currentSession && proto.previousSessions.length === 0) {
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throw new Error('toProtobuf: Record had no sessions!');
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}
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return proto;
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}
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function toProtobufSession(
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session: SessionType,
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ourData: LocalUserDataType
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): signal.proto.storage.SessionStructure {
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const proto = new SessionStructure();
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// Core Fields
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proto.aliceBaseKey = binaryToUint8Array(session, 'indexInfo.baseKey', 33);
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proto.localIdentityPublic = new Uint8Array(ourData.identityKeyPublic);
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proto.localRegistrationId = ourData.registrationId;
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proto.previousCounter = getInteger(session, 'currentRatchet.previousCounter');
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proto.remoteIdentityPublic = binaryToUint8Array(
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session,
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'indexInfo.remoteIdentityKey',
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33
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);
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proto.remoteRegistrationId = getInteger(session, 'registrationId');
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proto.rootKey = binaryToUint8Array(session, 'currentRatchet.rootKey', 32);
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proto.sessionVersion = 1;
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// Note: currently unused
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// proto.needsRefresh = null;
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// Pending PreKey
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if (session.pendingPreKey) {
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proto.pendingPreKey = new signal.proto.storage.SessionStructure.PendingPreKey();
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proto.pendingPreKey.baseKey = binaryToUint8Array(
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session,
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'pendingPreKey.baseKey',
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33
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);
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proto.pendingPreKey.signedPreKeyId = getInteger(
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session,
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'pendingPreKey.signedKeyId'
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);
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if (session.pendingPreKey.preKeyId !== undefined) {
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proto.pendingPreKey.preKeyId = getInteger(
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session,
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'pendingPreKey.preKeyId'
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);
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}
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}
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// Sender Chain
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const senderBaseKey = session.currentRatchet?.ephemeralKeyPair?.pubKey;
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if (!senderBaseKey) {
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throw new Error('toProtobufSession: No sender base key!');
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}
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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const senderChain = (session as any)[senderBaseKey] as ChainType | undefined;
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if (!senderChain) {
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throw new Error(
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'toProtobufSession: No matching chain found with senderBaseKey!'
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);
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}
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if (senderChain.chainType !== 1) {
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throw new Error(
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`toProtobufSession: Expected sender chain type for senderChain, got ${senderChain.chainType}`
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);
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}
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const protoSenderChain = toProtobufChain(senderChain);
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protoSenderChain.senderRatchetKey = binaryToUint8Array(
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session,
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'currentRatchet.ephemeralKeyPair.pubKey',
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33
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);
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protoSenderChain.senderRatchetKeyPrivate = binaryToUint8Array(
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session,
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'currentRatchet.ephemeralKeyPair.privKey',
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32
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);
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proto.senderChain = protoSenderChain;
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// First Receiver Chain
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proto.receiverChains = [];
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const firstReceiverChainBaseKey =
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session.currentRatchet?.lastRemoteEphemeralKey;
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if (!firstReceiverChainBaseKey) {
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throw new Error('toProtobufSession: No receiver base key!');
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}
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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const firstReceiverChain = (session as any)[firstReceiverChainBaseKey] as
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| ChainType
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| undefined;
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// If the session was just initialized, then there will be no receiver chain
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if (firstReceiverChain) {
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const protoFirstReceiverChain = toProtobufChain(firstReceiverChain);
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if (firstReceiverChain.chainType !== 2) {
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throw new Error(
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`toProtobufSession: Expected receiver chain type for firstReceiverChain, got ${firstReceiverChain.chainType}`
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);
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}
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protoFirstReceiverChain.senderRatchetKey = binaryToUint8Array(
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session,
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'currentRatchet.lastRemoteEphemeralKey',
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33
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);
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proto.receiverChains.push(protoFirstReceiverChain);
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}
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// Old Receiver Chains
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const oldChains = (session.oldRatchetList || [])
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.slice(0)
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.sort((left, right) => (right.added || 0) - (left.added || 0));
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oldChains.forEach(oldRatchet => {
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const baseKey = oldRatchet.ephemeralKey;
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if (!baseKey) {
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throw new Error('toProtobufSession: No base key for old receiver chain!');
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}
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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const chain = (session as any)[baseKey] as ChainType | undefined;
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if (!chain) {
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throw new Error(
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'toProtobufSession: No chain for old receiver chain base key!'
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);
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}
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if (chain.chainType !== 2) {
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throw new Error(
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`toProtobufSession: Expected receiver chain type, got ${chain.chainType}`
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);
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}
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const protoChain = toProtobufChain(chain);
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protoChain.senderRatchetKey = binaryToUint8Array(
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oldRatchet,
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'ephemeralKey',
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33
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);
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proto.receiverChains.push(protoChain);
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});
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return proto;
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}
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function toProtobufChain(
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chain: ChainType
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): signal.proto.storage.SessionStructure.Chain {
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const proto = new Chain();
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const protoChainKey = new Chain.ChainKey();
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protoChainKey.index = getInteger(chain, 'chainKey.counter');
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if (chain.chainKey?.key !== undefined) {
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protoChainKey.key = binaryToUint8Array(chain, 'chainKey.key', 32);
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}
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proto.chainKey = protoChainKey;
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const messageKeys = Object.entries(chain.messageKeys || {});
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proto.messageKeys = messageKeys.map(entry => {
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const protoMessageKey = new SessionStructure.Chain.MessageKey();
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protoMessageKey.index = getInteger(entry, '0');
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const key = binaryToUint8Array(entry, '1', 32);
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const { cipherKey, macKey, iv } = translateMessageKey(key);
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protoMessageKey.cipherKey = new Uint8Array(cipherKey);
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protoMessageKey.macKey = new Uint8Array(macKey);
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protoMessageKey.iv = new Uint8Array(iv);
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return protoMessageKey;
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});
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return proto;
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}
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// Utility functions
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const WHISPER_MESSAGE_KEYS = 'WhisperMessageKeys';
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function deriveSecrets(
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input: ArrayBuffer,
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salt: ArrayBuffer,
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info: ArrayBuffer
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): Array<ArrayBuffer> {
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const hkdf = HKDF.new(3);
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const output = hkdf.deriveSecrets(
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3 * 32,
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Buffer.from(input),
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Buffer.from(info),
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Buffer.from(salt)
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);
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return [
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typedArrayToArrayBuffer(output.slice(0, 32)),
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typedArrayToArrayBuffer(output.slice(32, 64)),
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typedArrayToArrayBuffer(output.slice(64, 96)),
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];
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}
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function translateMessageKey(key: Uint8Array) {
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const input = key.buffer;
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const salt = new ArrayBuffer(32);
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const info = bytesFromString(WHISPER_MESSAGE_KEYS);
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const [cipherKey, macKey, ivContainer] = deriveSecrets(input, salt, info);
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return {
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cipherKey,
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macKey,
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iv: ivContainer.slice(0, 16),
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};
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}
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function binaryToUint8Array(
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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object: any,
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path: string,
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length: number
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): Uint8Array {
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const target = get(object, path);
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if (target === null || target === undefined) {
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throw new Error(`binaryToUint8Array: Falsey path ${path}`);
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}
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if (!isString(target)) {
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throw new Error(`binaryToUint8Array: String not found at path ${path}`);
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}
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const buffer = fromEncodedBinaryToArrayBuffer(target);
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if (length && buffer.byteLength !== length) {
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throw new Error(
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`binaryToUint8Array: Got unexpected length ${buffer.byteLength} instead of ${length} at path ${path}`
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);
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}
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return new Uint8Array(buffer);
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}
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// eslint-disable-next-line @typescript-eslint/no-explicit-any
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function getInteger(object: any, path: string): number {
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const target = get(object, path);
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if (target === null || target === undefined) {
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throw new Error(`getInteger: Falsey path ${path}`);
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}
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if (isString(target)) {
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const result = parseInt(target, 10);
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if (!isFinite(result)) {
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throw new Error(
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`getInteger: Value could not be parsed as number at ${path}: {target}`
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);
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}
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if (!isInteger(result)) {
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throw new Error(
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`getInteger: Parsed value not an integer at ${path}: {target}`
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);
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}
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return result;
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}
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if (!isInteger(target)) {
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throw new Error(`getInteger: Value not an integer at ${path}: {target}`);
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}
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return target;
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}
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