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bitwarden-browser/src/services/crypto.service.ts
Matt Gibson 79e6d012c5
Use organization api key for auth (#382)
* Create UserService for Api Keys

* Limit scope request for organization keys

* Expose necessary services for org key-based auth service

* Linter fixes

* Add public import models

Since public import is tied tightly to the private api, constructors are
provided to maintain coupling in case of changes

* Do not parallelize file access

This storage is sometims backed by lowdb files. Parallel writes can
cause issues.

* Match file name to class

* Serialize storageService promises

* Prefer multiple awaits to .then chains

* Linter fixes
2021-05-19 14:12:08 -05:00

767 lines
27 KiB
TypeScript

import * as bigInt from 'big-integer';
import { EncryptionType } from '../enums/encryptionType';
import { KdfType } from '../enums/kdfType';
import { EncArrayBuffer } from '../models/domain/encArrayBuffer';
import { EncryptedObject } from '../models/domain/encryptedObject';
import { EncString } from '../models/domain/encString';
import { SymmetricCryptoKey } from '../models/domain/symmetricCryptoKey';
import { ProfileOrganizationResponse } from '../models/response/profileOrganizationResponse';
import { CryptoService as CryptoServiceAbstraction } from '../abstractions/crypto.service';
import { CryptoFunctionService } from '../abstractions/cryptoFunction.service';
import { LogService } from '../abstractions/log.service';
import { PlatformUtilsService } from '../abstractions/platformUtils.service';
import { StorageService } from '../abstractions/storage.service';
import { ConstantsService } from './constants.service';
import { sequentialize } from '../misc/sequentialize';
import { Utils } from '../misc/utils';
import { EEFLongWordList } from '../misc/wordlist';
const Keys = {
key: 'key', // Master Key
encOrgKeys: 'encOrgKeys',
encPrivateKey: 'encPrivateKey',
encKey: 'encKey', // Generated Symmetric Key
keyHash: 'keyHash',
};
export class CryptoService implements CryptoServiceAbstraction {
private key: SymmetricCryptoKey;
private encKey: SymmetricCryptoKey;
private legacyEtmKey: SymmetricCryptoKey;
private keyHash: string;
private publicKey: ArrayBuffer;
private privateKey: ArrayBuffer;
private orgKeys: Map<string, SymmetricCryptoKey>;
constructor(private storageService: StorageService, private secureStorageService: StorageService,
private cryptoFunctionService: CryptoFunctionService, private platformUtilService: PlatformUtilsService,
private logService: LogService) {
}
async setKey(key: SymmetricCryptoKey): Promise<any> {
this.key = key;
if (!await this.shouldStoreKey()) {
return;
}
return this.secureStorageService.save(Keys.key, key.keyB64);
}
setKeyHash(keyHash: string): Promise<{}> {
this.keyHash = keyHash;
return this.storageService.save(Keys.keyHash, keyHash);
}
async setEncKey(encKey: string): Promise<{}> {
if (encKey == null) {
return;
}
await this.storageService.save(Keys.encKey, encKey);
this.encKey = null;
}
async setEncPrivateKey(encPrivateKey: string): Promise<{}> {
if (encPrivateKey == null) {
return;
}
await this.storageService.save(Keys.encPrivateKey, encPrivateKey);
this.privateKey = null;
}
setOrgKeys(orgs: ProfileOrganizationResponse[]): Promise<{}> {
const orgKeys: any = {};
orgs.forEach(org => {
orgKeys[org.id] = org.key;
});
this.orgKeys = null;
return this.storageService.save(Keys.encOrgKeys, orgKeys);
}
async getKey(): Promise<SymmetricCryptoKey> {
if (this.key != null) {
return this.key;
}
const key = await this.secureStorageService.get<string>(Keys.key);
if (key != null) {
if (!await this.shouldStoreKey()) {
this.logService.warning('Throwing away stored key since settings have changed');
this.secureStorageService.remove(Keys.key);
return null;
}
const symmetricKey = new SymmetricCryptoKey(Utils.fromB64ToArray(key).buffer);
if (!await this.validateKey(symmetricKey)) {
this.logService.warning('Wrong key, throwing away stored key');
this.secureStorageService.remove(Keys.key);
return null;
}
this.key = symmetricKey;
}
return key == null ? null : this.key;
}
async getKeyHash(): Promise<string> {
if (this.keyHash != null) {
return this.keyHash;
}
const keyHash = await this.storageService.get<string>(Keys.keyHash);
if (keyHash != null) {
this.keyHash = keyHash;
}
return keyHash == null ? null : this.keyHash;
}
@sequentialize(() => 'getEncKey')
async getEncKey(key: SymmetricCryptoKey = null): Promise<SymmetricCryptoKey> {
if (this.encKey != null) {
return this.encKey;
}
const encKey = await this.storageService.get<string>(Keys.encKey);
if (encKey == null) {
return null;
}
if (key == null) {
key = await this.getKey();
}
if (key == null) {
return null;
}
let decEncKey: ArrayBuffer;
const encKeyCipher = new EncString(encKey);
if (encKeyCipher.encryptionType === EncryptionType.AesCbc256_B64) {
decEncKey = await this.decryptToBytes(encKeyCipher, key);
} else if (encKeyCipher.encryptionType === EncryptionType.AesCbc256_HmacSha256_B64) {
const newKey = await this.stretchKey(key);
decEncKey = await this.decryptToBytes(encKeyCipher, newKey);
} else {
throw new Error('Unsupported encKey type.');
}
if (decEncKey == null) {
return null;
}
this.encKey = new SymmetricCryptoKey(decEncKey);
return this.encKey;
}
async getPublicKey(): Promise<ArrayBuffer> {
if (this.publicKey != null) {
return this.publicKey;
}
const privateKey = await this.getPrivateKey();
if (privateKey == null) {
return null;
}
this.publicKey = await this.cryptoFunctionService.rsaExtractPublicKey(privateKey);
return this.publicKey;
}
async getPrivateKey(): Promise<ArrayBuffer> {
if (this.privateKey != null) {
return this.privateKey;
}
const encPrivateKey = await this.storageService.get<string>(Keys.encPrivateKey);
if (encPrivateKey == null) {
return null;
}
this.privateKey = await this.decryptToBytes(new EncString(encPrivateKey), null);
return this.privateKey;
}
async getFingerprint(userId: string, publicKey?: ArrayBuffer): Promise<string[]> {
if (publicKey == null) {
publicKey = await this.getPublicKey();
}
if (publicKey === null) {
throw new Error('No public key available.');
}
const keyFingerprint = await this.cryptoFunctionService.hash(publicKey, 'sha256');
const userFingerprint = await this.cryptoFunctionService.hkdfExpand(keyFingerprint, userId, 32, 'sha256');
return this.hashPhrase(userFingerprint);
}
@sequentialize(() => 'getOrgKeys')
async getOrgKeys(): Promise<Map<string, SymmetricCryptoKey>> {
if (this.orgKeys != null && this.orgKeys.size > 0) {
return this.orgKeys;
}
const encOrgKeys = await this.storageService.get<any>(Keys.encOrgKeys);
if (encOrgKeys == null) {
return null;
}
const orgKeys: Map<string, SymmetricCryptoKey> = new Map<string, SymmetricCryptoKey>();
let setKey = false;
for (const orgId in encOrgKeys) {
if (!encOrgKeys.hasOwnProperty(orgId)) {
continue;
}
const decValue = await this.rsaDecrypt(encOrgKeys[orgId]);
orgKeys.set(orgId, new SymmetricCryptoKey(decValue));
setKey = true;
}
if (setKey) {
this.orgKeys = orgKeys;
}
return this.orgKeys;
}
async getOrgKey(orgId: string): Promise<SymmetricCryptoKey> {
if (orgId == null) {
return null;
}
const orgKeys = await this.getOrgKeys();
if (orgKeys == null || !orgKeys.has(orgId)) {
return null;
}
return orgKeys.get(orgId);
}
async hasKey(): Promise<boolean> {
return (await this.getKey()) != null;
}
async hasEncKey(): Promise<boolean> {
const encKey = await this.storageService.get<string>(Keys.encKey);
return encKey != null;
}
clearKey(): Promise<any> {
this.key = this.legacyEtmKey = null;
return this.secureStorageService.remove(Keys.key);
}
clearKeyHash(): Promise<any> {
this.keyHash = null;
return this.storageService.remove(Keys.keyHash);
}
clearEncKey(memoryOnly?: boolean): Promise<any> {
this.encKey = null;
if (memoryOnly) {
return Promise.resolve();
}
return this.storageService.remove(Keys.encKey);
}
clearKeyPair(memoryOnly?: boolean): Promise<any> {
this.privateKey = null;
this.publicKey = null;
if (memoryOnly) {
return Promise.resolve();
}
return this.storageService.remove(Keys.encPrivateKey);
}
clearOrgKeys(memoryOnly?: boolean): Promise<any> {
this.orgKeys = null;
if (memoryOnly) {
return Promise.resolve();
}
return this.storageService.remove(Keys.encOrgKeys);
}
clearPinProtectedKey(): Promise<any> {
return this.storageService.remove(ConstantsService.pinProtectedKey);
}
async clearKeys(): Promise<any> {
await this.clearEncKey();
await this.clearKeyHash();
await this.clearOrgKeys();
await this.clearEncKey();
await this.clearKeyPair();
await this.clearPinProtectedKey();
}
async toggleKey(): Promise<any> {
const key = await this.getKey();
const option = await this.storageService.get(ConstantsService.vaultTimeoutKey);
const biometric = await this.storageService.get(ConstantsService.biometricUnlockKey);
if ((!biometric && this.platformUtilService.supportsSecureStorage()) && (option != null || option === 0)) {
// if we have a lock option set, clear the key
await this.clearKey();
this.key = key;
return;
}
await this.setKey(key);
}
async makeKey(password: string, salt: string, kdf: KdfType, kdfIterations: number):
Promise<SymmetricCryptoKey> {
let key: ArrayBuffer = null;
if (kdf == null || kdf === KdfType.PBKDF2_SHA256) {
if (kdfIterations == null) {
kdfIterations = 5000;
} else if (kdfIterations < 5000) {
throw new Error('PBKDF2 iteration minimum is 5000.');
}
key = await this.cryptoFunctionService.pbkdf2(password, salt, 'sha256', kdfIterations);
} else {
throw new Error('Unknown Kdf.');
}
return new SymmetricCryptoKey(key);
}
async makeKeyFromPin(pin: string, salt: string, kdf: KdfType, kdfIterations: number,
protectedKeyCs: EncString = null):
Promise<SymmetricCryptoKey> {
if (protectedKeyCs == null) {
const pinProtectedKey = await this.storageService.get<string>(ConstantsService.pinProtectedKey);
if (pinProtectedKey == null) {
throw new Error('No PIN protected key found.');
}
protectedKeyCs = new EncString(pinProtectedKey);
}
const pinKey = await this.makePinKey(pin, salt, kdf, kdfIterations);
const decKey = await this.decryptToBytes(protectedKeyCs, pinKey);
return new SymmetricCryptoKey(decKey);
}
async makeShareKey(): Promise<[EncString, SymmetricCryptoKey]> {
const shareKey = await this.cryptoFunctionService.randomBytes(64);
const publicKey = await this.getPublicKey();
const encShareKey = await this.rsaEncrypt(shareKey, publicKey);
return [encShareKey, new SymmetricCryptoKey(shareKey)];
}
async makeKeyPair(key?: SymmetricCryptoKey): Promise<[string, EncString]> {
const keyPair = await this.cryptoFunctionService.rsaGenerateKeyPair(2048);
const publicB64 = Utils.fromBufferToB64(keyPair[0]);
const privateEnc = await this.encrypt(keyPair[1], key);
return [publicB64, privateEnc];
}
async makePinKey(pin: string, salt: string, kdf: KdfType, kdfIterations: number): Promise<SymmetricCryptoKey> {
const pinKey = await this.makeKey(pin, salt, kdf, kdfIterations);
return await this.stretchKey(pinKey);
}
async makeSendKey(keyMaterial: ArrayBuffer): Promise<SymmetricCryptoKey> {
const sendKey = await this.cryptoFunctionService.hkdf(keyMaterial, 'bitwarden-send', 'send', 64, 'sha256');
return new SymmetricCryptoKey(sendKey);
}
async hashPassword(password: string, key: SymmetricCryptoKey): Promise<string> {
if (key == null) {
key = await this.getKey();
}
if (password == null || key == null) {
throw new Error('Invalid parameters.');
}
const hash = await this.cryptoFunctionService.pbkdf2(key.key, password, 'sha256', 1);
return Utils.fromBufferToB64(hash);
}
async makeEncKey(key: SymmetricCryptoKey): Promise<[SymmetricCryptoKey, EncString]> {
const theKey = await this.getKeyForEncryption(key);
const encKey = await this.cryptoFunctionService.randomBytes(64);
return this.buildEncKey(theKey, encKey);
}
async remakeEncKey(key: SymmetricCryptoKey, encKey?: SymmetricCryptoKey): Promise<[SymmetricCryptoKey, EncString]> {
if (encKey == null) {
encKey = await this.getEncKey();
}
return this.buildEncKey(key, encKey.key);
}
async encrypt(plainValue: string | ArrayBuffer, key?: SymmetricCryptoKey): Promise<EncString> {
if (plainValue == null) {
return Promise.resolve(null);
}
let plainBuf: ArrayBuffer;
if (typeof (plainValue) === 'string') {
plainBuf = Utils.fromUtf8ToArray(plainValue).buffer;
} else {
plainBuf = plainValue;
}
const encObj = await this.aesEncrypt(plainBuf, key);
const iv = Utils.fromBufferToB64(encObj.iv);
const data = Utils.fromBufferToB64(encObj.data);
const mac = encObj.mac != null ? Utils.fromBufferToB64(encObj.mac) : null;
return new EncString(encObj.key.encType, data, iv, mac);
}
async encryptToBytes(plainValue: ArrayBuffer, key?: SymmetricCryptoKey): Promise<EncArrayBuffer> {
const encValue = await this.aesEncrypt(plainValue, key);
let macLen = 0;
if (encValue.mac != null) {
macLen = encValue.mac.byteLength;
}
const encBytes = new Uint8Array(1 + encValue.iv.byteLength + macLen + encValue.data.byteLength);
encBytes.set([encValue.key.encType]);
encBytes.set(new Uint8Array(encValue.iv), 1);
if (encValue.mac != null) {
encBytes.set(new Uint8Array(encValue.mac), 1 + encValue.iv.byteLength);
}
encBytes.set(new Uint8Array(encValue.data), 1 + encValue.iv.byteLength + macLen);
return new EncArrayBuffer(encBytes.buffer);
}
async rsaEncrypt(data: ArrayBuffer, publicKey?: ArrayBuffer): Promise<EncString> {
if (publicKey == null) {
publicKey = await this.getPublicKey();
}
if (publicKey == null) {
throw new Error('Public key unavailable.');
}
const encBytes = await this.cryptoFunctionService.rsaEncrypt(data, publicKey, 'sha1');
return new EncString(EncryptionType.Rsa2048_OaepSha1_B64, Utils.fromBufferToB64(encBytes));
}
async rsaDecrypt(encValue: string): Promise<ArrayBuffer> {
const headerPieces = encValue.split('.');
let encType: EncryptionType = null;
let encPieces: string[];
if (headerPieces.length === 1) {
encType = EncryptionType.Rsa2048_OaepSha256_B64;
encPieces = [headerPieces[0]];
} else if (headerPieces.length === 2) {
try {
encType = parseInt(headerPieces[0], null);
encPieces = headerPieces[1].split('|');
} catch (e) { }
}
switch (encType) {
case EncryptionType.Rsa2048_OaepSha256_B64:
case EncryptionType.Rsa2048_OaepSha1_B64:
// HmacSha256 types are deprecated
case EncryptionType.Rsa2048_OaepSha256_HmacSha256_B64:
case EncryptionType.Rsa2048_OaepSha1_HmacSha256_B64:
break;
default:
throw new Error('encType unavailable.');
}
if (encPieces == null || encPieces.length <= 0) {
throw new Error('encPieces unavailable.');
}
const data = Utils.fromB64ToArray(encPieces[0]).buffer;
const privateKey = await this.getPrivateKey();
if (privateKey == null) {
throw new Error('No private key.');
}
let alg: 'sha1' | 'sha256' = 'sha1';
switch (encType) {
case EncryptionType.Rsa2048_OaepSha256_B64:
case EncryptionType.Rsa2048_OaepSha256_HmacSha256_B64:
alg = 'sha256';
break;
case EncryptionType.Rsa2048_OaepSha1_B64:
case EncryptionType.Rsa2048_OaepSha1_HmacSha256_B64:
break;
default:
throw new Error('encType unavailable.');
}
return this.cryptoFunctionService.rsaDecrypt(data, privateKey, alg);
}
async decryptToBytes(encString: EncString, key?: SymmetricCryptoKey): Promise<ArrayBuffer> {
const iv = Utils.fromB64ToArray(encString.iv).buffer;
const data = Utils.fromB64ToArray(encString.data).buffer;
const mac = encString.mac ? Utils.fromB64ToArray(encString.mac).buffer : null;
const decipher = await this.aesDecryptToBytes(encString.encryptionType, data, iv, mac, key);
if (decipher == null) {
return null;
}
return decipher;
}
async decryptToUtf8(encString: EncString, key?: SymmetricCryptoKey): Promise<string> {
return await this.aesDecryptToUtf8(encString.encryptionType, encString.data,
encString.iv, encString.mac, key);
}
async decryptFromBytes(encBuf: ArrayBuffer, key: SymmetricCryptoKey): Promise<ArrayBuffer> {
if (encBuf == null) {
throw new Error('no encBuf.');
}
const encBytes = new Uint8Array(encBuf);
const encType = encBytes[0];
let ctBytes: Uint8Array = null;
let ivBytes: Uint8Array = null;
let macBytes: Uint8Array = null;
switch (encType) {
case EncryptionType.AesCbc128_HmacSha256_B64:
case EncryptionType.AesCbc256_HmacSha256_B64:
if (encBytes.length <= 49) { // 1 + 16 + 32 + ctLength
return null;
}
ivBytes = encBytes.slice(1, 17);
macBytes = encBytes.slice(17, 49);
ctBytes = encBytes.slice(49);
break;
case EncryptionType.AesCbc256_B64:
if (encBytes.length <= 17) { // 1 + 16 + ctLength
return null;
}
ivBytes = encBytes.slice(1, 17);
ctBytes = encBytes.slice(17);
break;
default:
return null;
}
return await this.aesDecryptToBytes(encType, ctBytes.buffer, ivBytes.buffer,
macBytes != null ? macBytes.buffer : null, key);
}
// EFForg/OpenWireless
// ref https://github.com/EFForg/OpenWireless/blob/master/app/js/diceware.js
async randomNumber(min: number, max: number): Promise<number> {
let rval = 0;
const range = max - min + 1;
const bitsNeeded = Math.ceil(Math.log2(range));
if (bitsNeeded > 53) {
throw new Error('We cannot generate numbers larger than 53 bits.');
}
const bytesNeeded = Math.ceil(bitsNeeded / 8);
const mask = Math.pow(2, bitsNeeded) - 1;
// 7776 -> (2^13 = 8192) -1 == 8191 or 0x00001111 11111111
// Fill a byte array with N random numbers
const byteArray = new Uint8Array(await this.cryptoFunctionService.randomBytes(bytesNeeded));
let p = (bytesNeeded - 1) * 8;
for (let i = 0; i < bytesNeeded; i++) {
rval += byteArray[i] * Math.pow(2, p);
p -= 8;
}
// Use & to apply the mask and reduce the number of recursive lookups
// tslint:disable-next-line
rval = rval & mask;
if (rval >= range) {
// Integer out of acceptable range
return this.randomNumber(min, max);
}
// Return an integer that falls within the range
return min + rval;
}
async validateKey(key: SymmetricCryptoKey) {
try {
const encPrivateKey = await this.storageService.get<string>(Keys.encPrivateKey);
if (encPrivateKey == null) {
return false;
}
const encKey = await this.getEncKey(key);
const privateKey = await this.decryptToBytes(new EncString(encPrivateKey), encKey);
await this.cryptoFunctionService.rsaExtractPublicKey(privateKey);
} catch (e) {
return false;
}
return true;
}
// Helpers
private async shouldStoreKey() {
const vaultTimeout = await this.storageService.get<number>(ConstantsService.vaultTimeoutKey);
const biometricUnlock = await this.storageService.get<boolean>(ConstantsService.biometricUnlockKey);
const biometricsEnabled = biometricUnlock && this.platformUtilService.supportsSecureStorage();
const noVaultTimeout = vaultTimeout == null;
return noVaultTimeout || biometricsEnabled;
}
private async aesEncrypt(data: ArrayBuffer, key: SymmetricCryptoKey): Promise<EncryptedObject> {
const obj = new EncryptedObject();
obj.key = await this.getKeyForEncryption(key);
obj.iv = await this.cryptoFunctionService.randomBytes(16);
obj.data = await this.cryptoFunctionService.aesEncrypt(data, obj.iv, obj.key.encKey);
if (obj.key.macKey != null) {
const macData = new Uint8Array(obj.iv.byteLength + obj.data.byteLength);
macData.set(new Uint8Array(obj.iv), 0);
macData.set(new Uint8Array(obj.data), obj.iv.byteLength);
obj.mac = await this.cryptoFunctionService.hmac(macData.buffer, obj.key.macKey, 'sha256');
}
return obj;
}
private async aesDecryptToUtf8(encType: EncryptionType, data: string, iv: string, mac: string,
key: SymmetricCryptoKey): Promise<string> {
const keyForEnc = await this.getKeyForEncryption(key);
const theKey = this.resolveLegacyKey(encType, keyForEnc);
if (theKey.macKey != null && mac == null) {
this.logService.error('mac required.');
return null;
}
if (theKey.encType !== encType) {
this.logService.error('encType unavailable.');
return null;
}
const fastParams = this.cryptoFunctionService.aesDecryptFastParameters(data, iv, mac, theKey);
if (fastParams.macKey != null && fastParams.mac != null) {
const computedMac = await this.cryptoFunctionService.hmacFast(fastParams.macData,
fastParams.macKey, 'sha256');
const macsEqual = await this.cryptoFunctionService.compareFast(fastParams.mac, computedMac);
if (!macsEqual) {
this.logService.error('mac failed.');
return null;
}
}
return this.cryptoFunctionService.aesDecryptFast(fastParams);
}
private async aesDecryptToBytes(encType: EncryptionType, data: ArrayBuffer, iv: ArrayBuffer,
mac: ArrayBuffer, key: SymmetricCryptoKey): Promise<ArrayBuffer> {
const keyForEnc = await this.getKeyForEncryption(key);
const theKey = this.resolveLegacyKey(encType, keyForEnc);
if (theKey.macKey != null && mac == null) {
return null;
}
if (theKey.encType !== encType) {
return null;
}
if (theKey.macKey != null && mac != null) {
const macData = new Uint8Array(iv.byteLength + data.byteLength);
macData.set(new Uint8Array(iv), 0);
macData.set(new Uint8Array(data), iv.byteLength);
const computedMac = await this.cryptoFunctionService.hmac(macData.buffer, theKey.macKey, 'sha256');
if (computedMac === null) {
return null;
}
const macsMatch = await this.cryptoFunctionService.compare(mac, computedMac);
if (!macsMatch) {
this.logService.error('mac failed.');
return null;
}
}
return await this.cryptoFunctionService.aesDecrypt(data, iv, theKey.encKey);
}
private async getKeyForEncryption(key?: SymmetricCryptoKey): Promise<SymmetricCryptoKey> {
if (key != null) {
return key;
}
const encKey = await this.getEncKey();
if (encKey != null) {
return encKey;
}
return await this.getKey();
}
private resolveLegacyKey(encType: EncryptionType, key: SymmetricCryptoKey): SymmetricCryptoKey {
if (encType === EncryptionType.AesCbc128_HmacSha256_B64 &&
key.encType === EncryptionType.AesCbc256_B64) {
// Old encrypt-then-mac scheme, make a new key
if (this.legacyEtmKey == null) {
this.legacyEtmKey = new SymmetricCryptoKey(key.key, EncryptionType.AesCbc128_HmacSha256_B64);
}
return this.legacyEtmKey;
}
return key;
}
private async stretchKey(key: SymmetricCryptoKey): Promise<SymmetricCryptoKey> {
const newKey = new Uint8Array(64);
const encKey = await this.cryptoFunctionService.hkdfExpand(key.key, 'enc', 32, 'sha256');
const macKey = await this.cryptoFunctionService.hkdfExpand(key.key, 'mac', 32, 'sha256');
newKey.set(new Uint8Array(encKey));
newKey.set(new Uint8Array(macKey), 32);
return new SymmetricCryptoKey(newKey.buffer);
}
private async hashPhrase(hash: ArrayBuffer, minimumEntropy: number = 64) {
const entropyPerWord = Math.log(EEFLongWordList.length) / Math.log(2);
let numWords = Math.ceil(minimumEntropy / entropyPerWord);
const hashArr = Array.from(new Uint8Array(hash));
const entropyAvailable = hashArr.length * 4;
if (numWords * entropyPerWord > entropyAvailable) {
throw new Error('Output entropy of hash function is too small');
}
const phrase: string[] = [];
let hashNumber = bigInt.fromArray(hashArr, 256);
while (numWords--) {
const remainder = hashNumber.mod(EEFLongWordList.length);
hashNumber = hashNumber.divide(EEFLongWordList.length);
phrase.push(EEFLongWordList[remainder as any]);
}
return phrase;
}
private async buildEncKey(key: SymmetricCryptoKey, encKey: ArrayBuffer)
: Promise<[SymmetricCryptoKey, EncString]> {
let encKeyEnc: EncString = null;
if (key.key.byteLength === 32) {
const newKey = await this.stretchKey(key);
encKeyEnc = await this.encrypt(encKey, newKey);
} else if (key.key.byteLength === 64) {
encKeyEnc = await this.encrypt(encKey, key);
} else {
throw new Error('Invalid key size.');
}
return [new SymmetricCryptoKey(encKey), encKeyEnc];
}
}