'          key = unhexlify(key)         iv = unhexlify(iv)         plaintext = unhexlify(plaintext)         ciphertext = unhexlify(ciphertext)          cipher = AES.new(key, AES.MODE_CBC, iv)         self.assertEqual(cipher.encrypt(plaintext), ciphertext)         cipher = AES.new(key, AES.MODE_CBC, iv)         self.assertEqual(cipher.decrypt(ciphertext), plaintext)      def test_aes_000(self):         key =           '0