docs: final byte[] crypto(final byte[] input, final int offset, final int len, final boolean decrypt)
  			throws InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException,
  			BadPaddingException {
  		aesCipher.init(decrypt ? Cipher.DECRYPT_MODE : Cipher.ENCRYPT_MODE, aesKey, aesIV);
  		return aesCipher.doFinal(input, offset, len);
  	}