Beispiel #1
0
  /**
   * Decrypts the given input data.
   *
   * @param in data to decrypt
   * @param k secret key
   * @param a encryption algorithm
   * @param ivl initialization vector length
   * @return decrypted data
   * @throws NoSuchAlgorithmException ex
   * @throws NoSuchPaddingException ex
   * @throws InvalidKeyException ex
   * @throws InvalidAlgorithmParameterException ex
   * @throws IllegalBlockSizeException ex
   * @throws BadPaddingException ex
   */
  private static byte[] decrypt(final byte[] in, final byte[] k, final byte[] a, final int ivl)
      throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
          InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {

    final SecretKeySpec keySpec = new SecretKeySpec(k, string(a));
    final Cipher cipher = Cipher.getInstance(string(ALGN.get(lc(a))));

    // extract iv from message beginning
    final byte[] iv = substring(in, 0, ivl);
    final IvParameterSpec ivspec = new IvParameterSpec(iv);
    cipher.init(Cipher.DECRYPT_MODE, keySpec, ivspec);
    return cipher.doFinal(substring(in, ivl, in.length));
  }
Beispiel #2
0
  /**
   * Encrypts the given input data.
   *
   * @param in input data to encrypt
   * @param k key
   * @param a encryption algorithm
   * @param ivl initialization vector length
   * @return encrypted input data
   * @throws InvalidKeyException ex
   * @throws InvalidAlgorithmParameterException ex
   * @throws NoSuchAlgorithmException ex
   * @throws NoSuchPaddingException ex
   * @throws IllegalBlockSizeException ex
   * @throws BadPaddingException ex
   */
  private static byte[] encrypt(final byte[] in, final byte[] k, final byte[] a, final int ivl)
      throws InvalidKeyException, InvalidAlgorithmParameterException, NoSuchAlgorithmException,
          NoSuchPaddingException, IllegalBlockSizeException, BadPaddingException {

    final Cipher cipher = Cipher.getInstance(string(ALGN.get(lc(a))));
    final SecretKeySpec kspec = new SecretKeySpec(k, string(a));
    // generate random iv. random iv is necessary to make the encryption of a
    // string look different every time it is encrypted.
    final byte[] iv = new byte[ivl];
    // create new random iv if encrypting
    final SecureRandom rand = SecureRandom.getInstance("SHA1PRNG");
    rand.nextBytes(iv);
    final IvParameterSpec ivspec = new IvParameterSpec(iv);

    // encrypt/decrypt
    cipher.init(Cipher.ENCRYPT_MODE, kspec, ivspec);
    final byte[] t = cipher.doFinal(in);
    // initialization vector is appended to the message for later decryption
    return concat(iv, t);
  }