We perform no encryption, we just encode the value as base64 and then
        decode it in decrypt().

def encrypt(self):
        """
        We perform no encryption, we just encode the value as base64 and then
        decode it in decrypt().
        """
        value = self.parameters.get("Plaintext")
        if isinstance(value, six.text_type):
            value = value.encode('utf-8')
        return json.dumps({"CiphertextBlob": base64.b64encode(value).decode("utf-8"), 'KeyId': 'key_id'})