proteus-hd/src/proteus/derived/DerivedSecrets.js

Signal Protocol (with header encryption) implementation for JavaScript. Based on Proteus.js.

/*
 * Wire
 * Copyright (C) 2016 Wire Swiss GmbH
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see http://www.gnu.org/licenses/.
 *
 */

'use strict';

const ClassUtil = require('../util/ClassUtil');
const DontCallConstructor = require('../errors/DontCallConstructor');
const KeyDerivationUtil = require('../util/KeyDerivationUtil');
const MemoryUtil = require('../util/MemoryUtil');

const CipherKey = require('./CipherKey');
const MacKey = require('./MacKey');
const HeadKey = require('./HeadKey');

/** @module derived */

/**
 * @class DerivedSecrets
 * @throws {DontCallConstructor}
 */
class DerivedSecrets {
  constructor() {
    throw new DontCallConstructor(this);
  }

  /**
   * @param {!Array<number>} input
   * @param {!Uint8Array} salt
   * @param {!string} info
   * @returns {DerivedSecrets} - `this`
   */
  static kdf_init(input, salt, info) {
    const byte_length = 128;

    const output_key_material = KeyDerivationUtil.hkdf(salt, input, info, byte_length);

    const cipher_key = new Uint8Array(output_key_material.buffer.slice(0, 32));
    const mac_key = new Uint8Array(output_key_material.buffer.slice(32, 64));
    const head_key = new Uint8Array(output_key_material.buffer.slice(64, 96));
    const next_head_key = new Uint8Array(output_key_material.buffer.slice(96, 128));

    MemoryUtil.zeroize(output_key_material.buffer);

    const ds = ClassUtil.new_instance(DerivedSecrets);
    /** @type {derived.CipherKey} */
    ds.cipher_key = CipherKey.new(cipher_key);
    /** @type {derived.MacKey} */
    ds.mac_key = MacKey.new(mac_key);
    /** @type {derived.HeadKey} */
    ds.head_key_alice = HeadKey.new(head_key);
    /** @type {derived.HeadKey} */
    ds.next_head_key_bob = HeadKey.new(next_head_key);
    return ds;
  }

  /**
   * @param {!Array<number>} input
   * @param {!Uint8Array} salt
   * @param {!string} info
   * @returns {DerivedSecrets} - `this`
   */
  static kdf(input, salt, info) {
    const byte_length = 96;

    const output_key_material = KeyDerivationUtil.hkdf(salt, input, info, byte_length);

    const cipher_key = new Uint8Array(output_key_material.buffer.slice(0, 32));
    const mac_key = new Uint8Array(output_key_material.buffer.slice(32, 64));
    const next_head_key = new Uint8Array(output_key_material.buffer.slice(64, 96));

    MemoryUtil.zeroize(output_key_material.buffer);

    const ds = ClassUtil.new_instance(DerivedSecrets);
    /** @type {derived.CipherKey} */
    ds.cipher_key = CipherKey.new(cipher_key);
    /** @type {derived.MacKey} */
    ds.mac_key = MacKey.new(mac_key);
    /** @type {derived.HeadKey} */
    ds.next_head_key = HeadKey.new(next_head_key);
    return ds;
  }

  /**
   * @param {!Array<number>} input - Initial key material (usually the Master Key) in byte array format
   * @param {!string} info - Key Derivation Data
   * @returns {DerivedSecrets}
   */
  static kdf_without_salt(input, info) {
    return this.kdf_init(input, new Uint8Array(0), info);
  }
}

module.exports = DerivedSecrets;