amazon-cognito-identity-js
Version:
Amazon Cognito Identity Provider JavaScript SDK
336 lines (289 loc) • 10.1 kB
JavaScript
/*!
* Copyright 2016 Amazon.com,
* Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Amazon Software License (the "License").
* You may not use this file except in compliance with the
* License. A copy of the License is located at
*
* http://aws.amazon.com/asl/
*
* or in the "license" file accompanying this file. This file is
* distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
* CONDITIONS OF ANY KIND, express or implied. See the License
* for the specific language governing permissions and
* limitations under the License.
*/
import { Buffer } from 'buffer/';
import CryptoJS from 'crypto-js/core';
import 'crypto-js/lib-typedarrays'; // necessary for crypto js
import SHA256 from 'crypto-js/sha256';
import HmacSHA256 from 'crypto-js/hmac-sha256';
const randomBytes = function(nBytes) {
return Buffer.from((CryptoJS.lib.WordArray.random(nBytes)).toString(), 'hex');
}
import BigInteger from './BigInteger';
const initN = 'FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1'
+ '29024E088A67CC74020BBEA63B139B22514A08798E3404DD'
+ 'EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245'
+ 'E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED'
+ 'EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE45B3D'
+ 'C2007CB8A163BF0598DA48361C55D39A69163FA8FD24CF5F'
+ '83655D23DCA3AD961C62F356208552BB9ED529077096966D'
+ '670C354E4ABC9804F1746C08CA18217C32905E462E36CE3B'
+ 'E39E772C180E86039B2783A2EC07A28FB5C55DF06F4C52C9'
+ 'DE2BCBF6955817183995497CEA956AE515D2261898FA0510'
+ '15728E5A8AAAC42DAD33170D04507A33A85521ABDF1CBA64'
+ 'ECFB850458DBEF0A8AEA71575D060C7DB3970F85A6E1E4C7'
+ 'ABF5AE8CDB0933D71E8C94E04A25619DCEE3D2261AD2EE6B'
+ 'F12FFA06D98A0864D87602733EC86A64521F2B18177B200C'
+ 'BBE117577A615D6C770988C0BAD946E208E24FA074E5AB31'
+ '43DB5BFCE0FD108E4B82D120A93AD2CAFFFFFFFFFFFFFFFF';
const newPasswordRequiredChallengeUserAttributePrefix = 'userAttributes.';
/** @class */
export default class AuthenticationHelper {
/**
* Constructs a new AuthenticationHelper object
* @param {string} PoolName Cognito user pool name.
*/
constructor(PoolName) {
this.N = new BigInteger(initN, 16);
this.g = new BigInteger('2', 16);
this.k = new BigInteger(this.hexHash(`00${this.N.toString(16)}0${this.g.toString(16)}`), 16);
this.smallAValue = this.generateRandomSmallA();
this.getLargeAValue(() => {});
this.infoBits = Buffer.from('Caldera Derived Key', 'utf8');
this.poolName = PoolName;
}
/**
* @returns {BigInteger} small A, a random number
*/
getSmallAValue() {
return this.smallAValue;
}
/**
* @param {nodeCallback<BigInteger>} callback Called with (err, largeAValue)
* @returns {void}
*/
getLargeAValue(callback) {
if (this.largeAValue) {
callback(null, this.largeAValue);
} else {
this.calculateA(this.smallAValue, (err, largeAValue) => {
if (err) {
callback(err, null);
}
this.largeAValue = largeAValue;
callback(null, this.largeAValue);
});
}
}
/**
* helper function to generate a random big integer
* @returns {BigInteger} a random value.
* @private
*/
generateRandomSmallA() {
const hexRandom = randomBytes(128).toString('hex');
const randomBigInt = new BigInteger(hexRandom, 16);
const smallABigInt = randomBigInt.mod(this.N);
return smallABigInt;
}
/**
* helper function to generate a random string
* @returns {string} a random value.
* @private
*/
generateRandomString() {
return randomBytes(40).toString('base64');
}
/**
* @returns {string} Generated random value included in password hash.
*/
getRandomPassword() {
return this.randomPassword;
}
/**
* @returns {string} Generated random value included in devices hash.
*/
getSaltDevices() {
return this.SaltToHashDevices;
}
/**
* @returns {string} Value used to verify devices.
*/
getVerifierDevices() {
return this.verifierDevices;
}
/**
* Generate salts and compute verifier.
* @param {string} deviceGroupKey Devices to generate verifier for.
* @param {string} username User to generate verifier for.
* @param {nodeCallback<null>} callback Called with (err, null)
* @returns {void}
*/
generateHashDevice(deviceGroupKey, username, callback) {
this.randomPassword = this.generateRandomString();
const combinedString = `${deviceGroupKey}${username}:${this.randomPassword}`;
const hashedString = this.hash(combinedString);
const hexRandom = randomBytes(16).toString('hex');
this.SaltToHashDevices = this.padHex(new BigInteger(hexRandom, 16));
this.g.modPow(
new BigInteger(this.hexHash(this.SaltToHashDevices + hashedString), 16),
this.N,
(err, verifierDevicesNotPadded) => {
if (err) {
callback(err, null);
}
this.verifierDevices = this.padHex(verifierDevicesNotPadded);
callback(null, null);
});
}
/**
* Calculate the client's public value A = g^a%N
* with the generated random number a
* @param {BigInteger} a Randomly generated small A.
* @param {nodeCallback<BigInteger>} callback Called with (err, largeAValue)
* @returns {void}
* @private
*/
calculateA(a, callback) {
this.g.modPow(a, this.N, (err, A) => {
if (err) {
callback(err, null);
}
if (A.mod(this.N).equals(BigInteger.ZERO)) {
callback(new Error('Illegal paramater. A mod N cannot be 0.'), null);
}
callback(null, A);
});
}
/**
* Calculate the client's value U which is the hash of A and B
* @param {BigInteger} A Large A value.
* @param {BigInteger} B Server B value.
* @returns {BigInteger} Computed U value.
* @private
*/
calculateU(A, B) {
this.UHexHash = this.hexHash(this.padHex(A) + this.padHex(B));
const finalU = new BigInteger(this.UHexHash, 16);
return finalU;
}
/**
* Calculate a hash from a bitArray
* @param {Buffer} buf Value to hash.
* @returns {String} Hex-encoded hash.
* @private
*/
hash(buf) {
const str = buf instanceof Buffer ? CryptoJS.lib.WordArray.create(buf) : buf;
const hashHex = SHA256(str).toString();
return (new Array(64 - hashHex.length).join('0')) + hashHex;
}
/**
* Calculate a hash from a hex string
* @param {String} hexStr Value to hash.
* @returns {String} Hex-encoded hash.
* @private
*/
hexHash(hexStr) {
return this.hash(Buffer.from(hexStr, 'hex'));
}
/**
* Standard hkdf algorithm
* @param {Buffer} ikm Input key material.
* @param {Buffer} salt Salt value.
* @returns {Buffer} Strong key material.
* @private
*/
computehkdf(ikm, salt) {
const infoBitsWordArray = CryptoJS.lib.WordArray.create(
Buffer.concat([
this.infoBits,
Buffer.from(String.fromCharCode(1), 'utf8'),
])
);
const ikmWordArray = ikm instanceof Buffer ? CryptoJS.lib.WordArray.create(ikm) : ikm;
const saltWordArray = salt instanceof Buffer ? CryptoJS.lib.WordArray.create(salt) : salt;
const prk = HmacSHA256(ikmWordArray, saltWordArray);
const hmac = HmacSHA256(infoBitsWordArray, prk);
return Buffer.from(hmac.toString(), 'hex').slice(0, 16);
}
/**
* Calculates the final hkdf based on computed S value, and computed U value and the key
* @param {String} username Username.
* @param {String} password Password.
* @param {BigInteger} serverBValue Server B value.
* @param {BigInteger} salt Generated salt.
* @param {nodeCallback<Buffer>} callback Called with (err, hkdfValue)
* @returns {void}
*/
getPasswordAuthenticationKey(username, password, serverBValue, salt, callback) {
if (serverBValue.mod(this.N).equals(BigInteger.ZERO)) {
throw new Error('B cannot be zero.');
}
this.UValue = this.calculateU(this.largeAValue, serverBValue);
if (this.UValue.equals(BigInteger.ZERO)) {
throw new Error('U cannot be zero.');
}
const usernamePassword = `${this.poolName}${username}:${password}`;
const usernamePasswordHash = this.hash(usernamePassword);
const xValue = new BigInteger(this.hexHash(this.padHex(salt) + usernamePasswordHash), 16);
this.calculateS(xValue, serverBValue, (err, sValue) => {
if (err) {
callback(err, null);
}
const hkdf = this.computehkdf(
Buffer.from(this.padHex(sValue), 'hex'),
Buffer.from(this.padHex(this.UValue.toString(16)), 'hex'));
callback(null, hkdf);
});
}
/**
* Calculates the S value used in getPasswordAuthenticationKey
* @param {BigInteger} xValue Salted password hash value.
* @param {BigInteger} serverBValue Server B value.
* @param {nodeCallback<string>} callback Called on success or error.
* @returns {void}
*/
calculateS(xValue, serverBValue, callback) {
this.g.modPow(xValue, this.N, (err, gModPowXN) => {
if (err) {
callback(err, null);
}
const intValue2 = serverBValue.subtract(this.k.multiply(gModPowXN));
intValue2.modPow(
this.smallAValue.add(this.UValue.multiply(xValue)),
this.N,
(err2, result) => {
if (err2) {
callback(err2, null);
}
callback(null, result.mod(this.N));
}
);
});
}
/**
* Return constant newPasswordRequiredChallengeUserAttributePrefix
* @return {newPasswordRequiredChallengeUserAttributePrefix} constant prefix value
*/
getNewPasswordRequiredChallengeUserAttributePrefix() {
return newPasswordRequiredChallengeUserAttributePrefix;
}
/**
* Converts a BigInteger (or hex string) to hex format padded with zeroes for hashing
* @param {BigInteger|String} bigInt Number or string to pad.
* @returns {String} Padded hex string.
*/
padHex(bigInt) {
let hashStr = bigInt.toString(16);
if (hashStr.length % 2 === 1) {
hashStr = `0${hashStr}`;
} else if ('89ABCDEFabcdef'.indexOf(hashStr[0]) !== -1) {
hashStr = `00${hashStr}`;
}
return hashStr;
}
}