386 lines
11 KiB
JavaScript
386 lines
11 KiB
JavaScript
/*
|
|
Copyright 2017 Vector Creations Ltd
|
|
Copyright 2020 The Matrix.org Foundation C.I.C.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
// polyfill textencoder if necessary
|
|
import * as TextEncodingUtf8 from 'text-encoding-utf-8';
|
|
let TextEncoder = window.TextEncoder;
|
|
if (!TextEncoder) {
|
|
TextEncoder = TextEncodingUtf8.TextEncoder;
|
|
}
|
|
let TextDecoder = window.TextDecoder;
|
|
if (!TextDecoder) {
|
|
TextDecoder = TextEncodingUtf8.TextDecoder;
|
|
}
|
|
|
|
import { _t } from '../languageHandler';
|
|
import SdkConfig from '../SdkConfig';
|
|
|
|
const subtleCrypto = window.crypto.subtle || window.crypto.webkitSubtle;
|
|
|
|
/**
|
|
* Make an Error object which has a friendlyText property which is already
|
|
* translated and suitable for showing to the user.
|
|
*
|
|
* @param {string} msg message for the exception
|
|
* @param {string} friendlyText
|
|
* @returns {Error}
|
|
*/
|
|
function friendlyError(msg, friendlyText) {
|
|
const e = new Error(msg);
|
|
e.friendlyText = friendlyText;
|
|
return e;
|
|
}
|
|
|
|
function cryptoFailMsg() {
|
|
return _t('Your browser does not support the required cryptography extensions');
|
|
}
|
|
|
|
/**
|
|
* Decrypt a megolm key file
|
|
*
|
|
* @param {ArrayBuffer} data file to decrypt
|
|
* @param {String} password
|
|
* @return {Promise<String>} promise for decrypted output
|
|
*
|
|
*
|
|
*/
|
|
export async function decryptMegolmKeyFile(data, password) {
|
|
const body = unpackMegolmKeyFile(data);
|
|
const brand = SdkConfig.get().brand;
|
|
|
|
// check we have a version byte
|
|
if (body.length < 1) {
|
|
throw friendlyError('Invalid file: too short',
|
|
_t('Not a valid %(brand)s keyfile', { brand }));
|
|
}
|
|
|
|
const version = body[0];
|
|
if (version !== 1) {
|
|
throw friendlyError('Unsupported version',
|
|
_t('Not a valid %(brand)s keyfile', { brand }));
|
|
}
|
|
|
|
const ciphertextLength = body.length-(1+16+16+4+32);
|
|
if (ciphertextLength < 0) {
|
|
throw friendlyError('Invalid file: too short',
|
|
_t('Not a valid %(brand)s keyfile', { brand }));
|
|
}
|
|
|
|
const salt = body.subarray(1, 1+16);
|
|
const iv = body.subarray(17, 17+16);
|
|
const iterations = body[33] << 24 | body[34] << 16 | body[35] << 8 | body[36];
|
|
const ciphertext = body.subarray(37, 37+ciphertextLength);
|
|
const hmac = body.subarray(-32);
|
|
|
|
const [aesKey, hmacKey] = await deriveKeys(salt, iterations, password);
|
|
const toVerify = body.subarray(0, -32);
|
|
|
|
let isValid;
|
|
try {
|
|
isValid = await subtleCrypto.verify(
|
|
{name: 'HMAC'},
|
|
hmacKey,
|
|
hmac,
|
|
toVerify,
|
|
);
|
|
} catch (e) {
|
|
throw friendlyError('subtleCrypto.verify failed: ' + e, cryptoFailMsg());
|
|
}
|
|
if (!isValid) {
|
|
throw friendlyError('hmac mismatch',
|
|
_t('Authentication check failed: incorrect password?'));
|
|
}
|
|
|
|
let plaintext;
|
|
try {
|
|
plaintext = await subtleCrypto.decrypt(
|
|
{
|
|
name: "AES-CTR",
|
|
counter: iv,
|
|
length: 64,
|
|
},
|
|
aesKey,
|
|
ciphertext,
|
|
);
|
|
} catch (e) {
|
|
throw friendlyError('subtleCrypto.decrypt failed: ' + e, cryptoFailMsg());
|
|
}
|
|
|
|
return new TextDecoder().decode(new Uint8Array(plaintext));
|
|
}
|
|
|
|
|
|
/**
|
|
* Encrypt a megolm key file
|
|
*
|
|
* @param {String} data
|
|
* @param {String} password
|
|
* @param {Object=} options
|
|
* @param {Number=} options.kdf_rounds Number of iterations to perform of the
|
|
* key-derivation function.
|
|
* @return {Promise<ArrayBuffer>} promise for encrypted output
|
|
*/
|
|
export async function encryptMegolmKeyFile(data, password, options) {
|
|
options = options || {};
|
|
const kdfRounds = options.kdf_rounds || 500000;
|
|
|
|
const salt = new Uint8Array(16);
|
|
window.crypto.getRandomValues(salt);
|
|
|
|
const iv = new Uint8Array(16);
|
|
window.crypto.getRandomValues(iv);
|
|
|
|
// clear bit 63 of the IV to stop us hitting the 64-bit counter boundary
|
|
// (which would mean we wouldn't be able to decrypt on Android). The loss
|
|
// of a single bit of iv is a price we have to pay.
|
|
iv[8] &= 0x7f;
|
|
|
|
const [aesKey, hmacKey] = await deriveKeys(salt, kdfRounds, password);
|
|
const encodedData = new TextEncoder().encode(data);
|
|
|
|
let ciphertext;
|
|
try {
|
|
ciphertext = await subtleCrypto.encrypt(
|
|
{
|
|
name: "AES-CTR",
|
|
counter: iv,
|
|
length: 64,
|
|
},
|
|
aesKey,
|
|
encodedData,
|
|
);
|
|
} catch (e) {
|
|
throw friendlyError('subtleCrypto.encrypt failed: ' + e, cryptoFailMsg());
|
|
}
|
|
|
|
const cipherArray = new Uint8Array(ciphertext);
|
|
const bodyLength = (1+salt.length+iv.length+4+cipherArray.length+32);
|
|
const resultBuffer = new Uint8Array(bodyLength);
|
|
let idx = 0;
|
|
resultBuffer[idx++] = 1; // version
|
|
resultBuffer.set(salt, idx); idx += salt.length;
|
|
resultBuffer.set(iv, idx); idx += iv.length;
|
|
resultBuffer[idx++] = kdfRounds >> 24;
|
|
resultBuffer[idx++] = (kdfRounds >> 16) & 0xff;
|
|
resultBuffer[idx++] = (kdfRounds >> 8) & 0xff;
|
|
resultBuffer[idx++] = kdfRounds & 0xff;
|
|
resultBuffer.set(cipherArray, idx); idx += cipherArray.length;
|
|
|
|
const toSign = resultBuffer.subarray(0, idx);
|
|
|
|
let hmac;
|
|
try {
|
|
hmac = await subtleCrypto.sign(
|
|
{name: 'HMAC'},
|
|
hmacKey,
|
|
toSign,
|
|
);
|
|
} catch (e) {
|
|
throw friendlyError('subtleCrypto.sign failed: ' + e, cryptoFailMsg());
|
|
}
|
|
|
|
|
|
const hmacArray = new Uint8Array(hmac);
|
|
resultBuffer.set(hmacArray, idx);
|
|
return packMegolmKeyFile(resultBuffer);
|
|
}
|
|
|
|
/**
|
|
* Derive the AES and HMAC-SHA-256 keys for the file
|
|
*
|
|
* @param {Unit8Array} salt salt for pbkdf
|
|
* @param {Number} iterations number of pbkdf iterations
|
|
* @param {String} password password
|
|
* @return {Promise<[CryptoKey, CryptoKey]>} promise for [aes key, hmac key]
|
|
*/
|
|
async function deriveKeys(salt, iterations, password) {
|
|
const start = new Date();
|
|
|
|
let key;
|
|
try {
|
|
key = await subtleCrypto.importKey(
|
|
'raw',
|
|
new TextEncoder().encode(password),
|
|
{name: 'PBKDF2'},
|
|
false,
|
|
['deriveBits'],
|
|
);
|
|
} catch (e) {
|
|
throw friendlyError('subtleCrypto.importKey failed: ' + e, cryptoFailMsg());
|
|
}
|
|
|
|
let keybits;
|
|
try {
|
|
keybits = await subtleCrypto.deriveBits(
|
|
{
|
|
name: 'PBKDF2',
|
|
salt: salt,
|
|
iterations: iterations,
|
|
hash: 'SHA-512',
|
|
},
|
|
key,
|
|
512,
|
|
);
|
|
} catch (e) {
|
|
throw friendlyError('subtleCrypto.deriveBits failed: ' + e, cryptoFailMsg());
|
|
}
|
|
|
|
const now = new Date();
|
|
console.log("E2e import/export: deriveKeys took " + (now - start) + "ms");
|
|
|
|
const aesKey = keybits.slice(0, 32);
|
|
const hmacKey = keybits.slice(32);
|
|
|
|
const aesProm = subtleCrypto.importKey(
|
|
'raw',
|
|
aesKey,
|
|
{name: 'AES-CTR'},
|
|
false,
|
|
['encrypt', 'decrypt'],
|
|
).catch((e) => {
|
|
throw friendlyError('subtleCrypto.importKey failed for AES key: ' + e, cryptoFailMsg());
|
|
});
|
|
|
|
const hmacProm = subtleCrypto.importKey(
|
|
'raw',
|
|
hmacKey,
|
|
{
|
|
name: 'HMAC',
|
|
hash: {name: 'SHA-256'},
|
|
},
|
|
false,
|
|
['sign', 'verify'],
|
|
).catch((e) => {
|
|
throw friendlyError('subtleCrypto.importKey failed for HMAC key: ' + e, cryptoFailMsg());
|
|
});
|
|
|
|
return await Promise.all([aesProm, hmacProm]);
|
|
}
|
|
|
|
const HEADER_LINE = '-----BEGIN MEGOLM SESSION DATA-----';
|
|
const TRAILER_LINE = '-----END MEGOLM SESSION DATA-----';
|
|
|
|
/**
|
|
* Unbase64 an ascii-armoured megolm key file
|
|
*
|
|
* Strips the header and trailer lines, and unbase64s the content
|
|
*
|
|
* @param {ArrayBuffer} data input file
|
|
* @return {Uint8Array} unbase64ed content
|
|
*/
|
|
function unpackMegolmKeyFile(data) {
|
|
// parse the file as a great big String. This should be safe, because there
|
|
// should be no non-ASCII characters, and it means that we can do string
|
|
// comparisons to find the header and footer, and feed it into window.atob.
|
|
const fileStr = new TextDecoder().decode(new Uint8Array(data));
|
|
|
|
// look for the start line
|
|
let lineStart = 0;
|
|
while (1) {
|
|
const lineEnd = fileStr.indexOf('\n', lineStart);
|
|
if (lineEnd < 0) {
|
|
throw new Error('Header line not found');
|
|
}
|
|
const line = fileStr.slice(lineStart, lineEnd).trim();
|
|
|
|
// start the next line after the newline
|
|
lineStart = lineEnd+1;
|
|
|
|
if (line === HEADER_LINE) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
const dataStart = lineStart;
|
|
|
|
// look for the end line
|
|
while (1) {
|
|
const lineEnd = fileStr.indexOf('\n', lineStart);
|
|
const line = fileStr.slice(lineStart, lineEnd < 0 ? undefined : lineEnd)
|
|
.trim();
|
|
if (line === TRAILER_LINE) {
|
|
break;
|
|
}
|
|
|
|
if (lineEnd < 0) {
|
|
throw new Error('Trailer line not found');
|
|
}
|
|
|
|
// start the next line after the newline
|
|
lineStart = lineEnd+1;
|
|
}
|
|
|
|
const dataEnd = lineStart;
|
|
return decodeBase64(fileStr.slice(dataStart, dataEnd));
|
|
}
|
|
|
|
/**
|
|
* ascii-armour a megolm key file
|
|
*
|
|
* base64s the content, and adds header and trailer lines
|
|
*
|
|
* @param {Uint8Array} data raw data
|
|
* @return {ArrayBuffer} formatted file
|
|
*/
|
|
function packMegolmKeyFile(data) {
|
|
// we split into lines before base64ing, because encodeBase64 doesn't deal
|
|
// terribly well with large arrays.
|
|
const LINE_LENGTH = (72 * 4 / 3);
|
|
const nLines = Math.ceil(data.length / LINE_LENGTH);
|
|
const lines = new Array(nLines + 3);
|
|
lines[0] = HEADER_LINE;
|
|
let o = 0;
|
|
let i;
|
|
for (i = 1; i <= nLines; i++) {
|
|
lines[i] = encodeBase64(data.subarray(o, o+LINE_LENGTH));
|
|
o += LINE_LENGTH;
|
|
}
|
|
lines[i++] = TRAILER_LINE;
|
|
lines[i] = '';
|
|
return (new TextEncoder().encode(lines.join('\n'))).buffer;
|
|
}
|
|
|
|
/**
|
|
* Encode a typed array of uint8 as base64.
|
|
* @param {Uint8Array} uint8Array The data to encode.
|
|
* @return {string} The base64.
|
|
*/
|
|
function encodeBase64(uint8Array) {
|
|
// Misinterpt the Uint8Array as Latin-1.
|
|
// window.btoa expects a unicode string with codepoints in the range 0-255.
|
|
const latin1String = String.fromCharCode.apply(null, uint8Array);
|
|
// Use the builtin base64 encoder.
|
|
return window.btoa(latin1String);
|
|
}
|
|
|
|
/**
|
|
* Decode a base64 string to a typed array of uint8.
|
|
* @param {string} base64 The base64 to decode.
|
|
* @return {Uint8Array} The decoded data.
|
|
*/
|
|
function decodeBase64(base64) {
|
|
// window.atob returns a unicode string with codepoints in the range 0-255.
|
|
const latin1String = window.atob(base64);
|
|
// Encode the string as a Uint8Array
|
|
const uint8Array = new Uint8Array(latin1String.length);
|
|
for (let i = 0; i < latin1String.length; i++) {
|
|
uint8Array[i] = latin1String.charCodeAt(i);
|
|
}
|
|
return uint8Array;
|
|
}
|