Overleaf/services/web/frontend/js/shared/utils/crypto.js

/**
 * From: https://github.com/pvorb/node-crypt/blob/master/crypt.js
 * Copyright © 2011, Paul Vorbach. All rights reserved.
 * Copyright © 2009, Jeff Mott. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of
 *    conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 *    conditions and the following disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 * 3. Neither the name Crypto-JS nor the names of its contributors may be used to endorse or
 *    promote products derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

// Convert a byte array to big-endian 32-bit words
export function bytesToWords(bytes) {
  const words = []
  for (let i = 0, b = 0; i < bytes.length; i++, b += 8)
    words[b >>> 5] |= bytes[i] << (24 - (b % 32))
  return words
}

// Convert big-endian 32-bit words to a byte array
export function wordsToBytes(words) {
  const bytes = []
  for (let b = 0; b < words.length * 32; b += 8)
    bytes.push((words[b >>> 5] >>> (24 - (b % 32))) & 0xff)
  return bytes
}