def decrypt(self, ciphertext):
        """
        Decrypt the given string using Twofish ECB.
        """
        if len(ciphertext) % 16:
            raise RuntimeError("Twofish ciphertext length must be a multiple of 16")
        plaintext = ""
        while len(ciphertext) >= 16:
            plaintext += self.twofish.decrypt(ciphertext[0:16])
            ciphertext = ciphertext[16:]
        return plaintext