def serialize(self, compact=False):
        """Serializes the object into a JWE token.

        :param compact(boolean): if True generates the compact
         representation, otherwise generates a standard JSON format.

        :raises InvalidJWEOperation: if the object cannot serialized
         with the compact representation and `compact` is True.
        :raises InvalidJWEOperation: if no recipients have been added
         to the object.
        """

        if 'ciphertext' not in self.objects:
            raise InvalidJWEOperation("No available ciphertext")

        if compact:
            for invalid in 'aad', 'unprotected':
                if invalid in self.objects:
                    raise InvalidJWEOperation(
                        "Can't use compact encoding when the '%s' parameter"
                        "is set" % invalid)
            if 'protected' not in self.objects:
                raise InvalidJWEOperation(
                    "Can't use compat encoding without protected headers")
            else:
                ph = json_decode(self.objects['protected'])
                for required in 'alg', 'enc':
                    if required not in ph:
                        raise InvalidJWEOperation(
                            "Can't use compat encoding, '%s' must be in the "
                            "protected header" % required)
            if 'recipients' in self.objects:
                if len(self.objects['recipients']) != 1:
                    raise InvalidJWEOperation("Invalid number of recipients")
                rec = self.objects['recipients'][0]
            else:
                rec = self.objects
            if 'header' in rec:
                # The AESGCMKW algorithm generates data (iv, tag) we put in the
                # per-recipient unpotected header by default. Move it to the
                # protected header and re-encrypt the payload, as the protected
                # header is used as additional authenticated data.
                h = json_decode(rec['header'])
                ph = json_decode(self.objects['protected'])
                nph = self._merge_headers(h, ph)
                self.objects['protected'] = json_encode(nph)
                jh = self._get_jose_header()
                alg, enc = self._get_alg_enc_from_headers(jh)
                self._encrypt(alg, enc, jh)
                del rec['header']

            return '.'.join([base64url_encode(self.objects['protected']),
                             base64url_encode(rec.get('encrypted_key', '')),
                             base64url_encode(self.objects['iv']),
                             base64url_encode(self.objects['ciphertext']),
                             base64url_encode(self.objects['tag'])])
        else:
            obj = self.objects
            enc = {'ciphertext': base64url_encode(obj['ciphertext']),
                   'iv': base64url_encode(obj['iv']),
                   'tag': base64url_encode(self.objects['tag'])}
            if 'protected' in obj:
                enc['protected'] = base64url_encode(obj['protected'])
            if 'unprotected' in obj:
                enc['unprotected'] = json_decode(obj['unprotected'])
            if 'aad' in obj:
                enc['aad'] = base64url_encode(obj['aad'])
            if 'recipients' in obj:
                enc['recipients'] = list()
                for rec in obj['recipients']:
                    e = dict()
                    if 'encrypted_key' in rec:
                        e['encrypted_key'] = \
                            base64url_encode(rec['encrypted_key'])
                    if 'header' in rec:
                        e['header'] = json_decode(rec['header'])
                    enc['recipients'].append(e)
            else:
                if 'encrypted_key' in obj:
                    enc['encrypted_key'] = \
                        base64url_encode(obj['encrypted_key'])
                if 'header' in obj:
                    enc['header'] = json_decode(obj['header'])
            return json_encode(enc)
Serializes the object into a JWE token.

        :param compact(boolean): if True generates the compact
         representation, otherwise generates a standard JSON format.

        :raises InvalidJWEOperation: if the object cannot serialized
         with the compact representation and `compact` is True.
        :raises InvalidJWEOperation: if no recipients have been added
         to the object.