try {
// Should internally generate an IV
// todo - allow user to set an IV
c.init(Cipher.WRAP_MODE, _key);
encryptedBytes = c.wrap(key);
} catch (InvalidKeyException ike) {
throw new XMLEncryptionException("empty", ike);
} catch (IllegalBlockSizeException ibse) {
throw new XMLEncryptionException("empty", ibse);
}