Function convertPasswordToHash

lib/utils/encryptor.js:26–46

* Convert a password into an encryption key * @param {string} password - The password * @param {string} hashAlgorithm - The hash algoritm * @param {string} saltValue - The salt value * @param {number} spinCount - The spin count * @param {number} keyBits - The length of the key in bits

(password, hashAlgorithm, saltValue, spinCount)

   * @returns {Buffer} The encryption key
   */
  convertPasswordToHash(password, hashAlgorithm, saltValue, spinCount) {
    hashAlgorithm = hashAlgorithm.toLowerCase();
    const hashes = crypto.getHashes();
    if (hashes.indexOf(hashAlgorithm) < 0) {
      throw new Error(`Hash algorithm '${hashAlgorithm}' not supported!`);
    }

    // Password must be in unicode buffer
    const passwordBuffer = Buffer.from(password, 'utf16le');
    // Generate the initial hash
    let key = this.hash(hashAlgorithm, Buffer.from(saltValue, 'base64'), passwordBuffer);
    // Now regenerate until spin count
    for (let i = 0; i < spinCount; i++) {
      const iterator = Buffer.alloc(4);
      // this is the 'special' element of Excel password hashing
      // that stops us from using crypto.pbkdf2()
      iterator.writeUInt32LE(i, 0);
      key = this.hash(hashAlgorithm, key, iterator);
    }
    return key.toString('base64');
  },
  /**
   * Generates cryptographically strong pseudo-random data.
   * @param size The size argument is a number indicating the number of bytes to generate.