124 lines
3.6 KiB
TypeScript
124 lines
3.6 KiB
TypeScript
// Copyright 2020 Signal Messenger, LLC
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// SPDX-License-Identifier: AGPL-3.0-only
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/* eslint-disable more/no-then */
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/* eslint-disable max-classes-per-file */
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import { KeyPairType } from '../libsignal.d';
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import { ProvisionEnvelopeClass } from '../textsecure.d';
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type ProvisionDecryptResult = {
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identityKeyPair: KeyPairType;
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number?: string;
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uuid?: string;
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provisioningCode?: string;
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userAgent?: string;
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readReceipts?: boolean;
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profileKey?: ArrayBuffer;
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};
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class ProvisioningCipherInner {
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keyPair?: KeyPairType;
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async decrypt(
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provisionEnvelope: ProvisionEnvelopeClass
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): Promise<ProvisionDecryptResult> {
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const masterEphemeral = provisionEnvelope.publicKey.toArrayBuffer();
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const message = provisionEnvelope.body.toArrayBuffer();
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if (new Uint8Array(message)[0] !== 1) {
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throw new Error('Bad version number on ProvisioningMessage');
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}
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const iv = message.slice(1, 16 + 1);
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const mac = message.slice(message.byteLength - 32, message.byteLength);
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const ivAndCiphertext = message.slice(0, message.byteLength - 32);
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const ciphertext = message.slice(16 + 1, message.byteLength - 32);
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if (!this.keyPair) {
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throw new Error('ProvisioningCipher.decrypt: No keypair!');
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}
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return window.libsignal.Curve.async
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.calculateAgreement(masterEphemeral, this.keyPair.privKey)
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.then(async ecRes =>
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window.libsignal.HKDF.deriveSecrets(
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ecRes,
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new ArrayBuffer(32),
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'TextSecure Provisioning Message'
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)
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)
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.then(async keys =>
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window.libsignal.crypto
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.verifyMAC(ivAndCiphertext, keys[1], mac, 32)
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.then(async () =>
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window.libsignal.crypto.decrypt(keys[0], ciphertext, iv)
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)
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)
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.then(async plaintext => {
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const provisionMessage = window.textsecure.protobuf.ProvisionMessage.decode(
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plaintext
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);
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const privKey = provisionMessage.identityKeyPrivate.toArrayBuffer();
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return window.libsignal.Curve.async
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.createKeyPair(privKey)
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.then(keyPair => {
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window.normalizeUuids(
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provisionMessage,
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['uuid'],
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'ProvisioningCipher.decrypt'
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);
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const ret: ProvisionDecryptResult = {
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identityKeyPair: keyPair,
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number: provisionMessage.number,
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uuid: provisionMessage.uuid,
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provisioningCode: provisionMessage.provisioningCode,
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userAgent: provisionMessage.userAgent,
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readReceipts: provisionMessage.readReceipts,
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};
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if (provisionMessage.profileKey) {
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ret.profileKey = provisionMessage.profileKey.toArrayBuffer();
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}
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return ret;
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});
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});
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}
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async getPublicKey(): Promise<ArrayBuffer> {
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return Promise.resolve()
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.then(async () => {
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if (!this.keyPair) {
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return window.libsignal.Curve.async
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.generateKeyPair()
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.then(keyPair => {
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this.keyPair = keyPair;
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});
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}
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return null;
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})
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.then(() => {
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if (!this.keyPair) {
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throw new Error('ProvisioningCipher.decrypt: No keypair!');
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}
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return this.keyPair.pubKey;
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});
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}
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}
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export default class ProvisioningCipher {
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constructor() {
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const inner = new ProvisioningCipherInner();
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this.decrypt = inner.decrypt.bind(inner);
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this.getPublicKey = inner.getPublicKey.bind(inner);
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}
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decrypt: (
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provisionEnvelope: ProvisionEnvelopeClass
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) => Promise<ProvisionDecryptResult>;
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getPublicKey: () => Promise<ArrayBuffer>;
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}
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