forked from mystiq/hydrogen-web
122 lines
3.7 KiB
TypeScript
122 lines
3.7 KiB
TypeScript
/*
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Copyright 2020 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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import type {Platform} from "../../platform/web/Platform.js";
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export type KeyDescriptionData = {
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algorithm: string;
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passphrase: {
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algorithm: string;
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iterations: number;
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salt: string;
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bits?: number;
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};
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mac: string;
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iv: string;
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}
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export class KeyDescription {
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private readonly _id: string;
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private readonly _keyDescription: KeyDescriptionData;
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constructor(id: string, keyDescription: KeyDescriptionData) {
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this._id = id;
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this._keyDescription = keyDescription;
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}
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get id(): string {
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return this._id;
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}
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get passphraseParams(): KeyDescriptionData["passphrase"] {
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return this._keyDescription?.passphrase;
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}
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get algorithm(): string {
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return this._keyDescription?.algorithm;
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}
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async isCompatible(key: Key, platform: Platform): Promise<boolean> {
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if (this.algorithm === "m.secret_storage.v1.aes-hmac-sha2") {
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const kd = this._keyDescription;
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if (kd.mac) {
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const otherMac = await calculateKeyMac(key.binaryKey, kd.iv, platform);
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return kd.mac === otherMac;
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} else if (kd.passphrase) {
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const kdOther = key.description._keyDescription;
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if (!kdOther.passphrase) {
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return false;
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}
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return kd.passphrase.algorithm === kdOther.passphrase.algorithm &&
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kd.passphrase.iterations === kdOther.passphrase.iterations &&
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kd.passphrase.salt === kdOther.passphrase.salt;
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}
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}
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return false;
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}
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}
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export class Key {
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private readonly _keyDescription: KeyDescription;
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private readonly _binaryKey: Uint8Array;
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constructor(keyDescription: KeyDescription, binaryKey: Uint8Array) {
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this._keyDescription = keyDescription;
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this._binaryKey = binaryKey;
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}
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withDescription(description: KeyDescription): Key {
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return new Key(description, this._binaryKey);
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}
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get description(): KeyDescription {
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return this._keyDescription;
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}
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get id(): string {
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return this._keyDescription.id;
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}
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get binaryKey(): Uint8Array {
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return this._binaryKey;
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}
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get algorithm(): string {
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return this._keyDescription.algorithm;
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}
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}
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async function calculateKeyMac(key: BufferSource, ivStr: string, platform: Platform): Promise<string> {
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const {crypto, encoding} = platform;
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const {utf8, base64} = encoding;
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const {derive, aes, hmac} = crypto;
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const iv = base64.decode(ivStr);
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// salt for HKDF, with 8 bytes of zeros
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const zerosalt = new Uint8Array(8);
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const ZERO_STR = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
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const info = utf8.encode("");
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const keybits = await derive.hkdf(key, zerosalt, info, "SHA-256", 512);
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const aesKey = keybits.slice(0, 32);
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const hmacKey = keybits.slice(32);
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const ciphertext = await aes.encryptCTR({key: aesKey, iv, data: utf8.encode(ZERO_STR)});
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const mac = await hmac.compute(hmacKey, ciphertext, "SHA-256");
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return base64.encode(mac);
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}
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