def METHOD_NAME(self):
    # Even if the input is repeated, the output should not be.
    encrypted = encrypt_binary(b"0" * 1_000_000, self.key)
    # The output should appear random, so any sequence of 64 bytes is
    # very unlikely to repeat.
    blocks = re.findall(".{64}", encrypted)
    self.assertEqual(len(blocks), len(set(blocks)))