SilcBuffer silc_channel_key_payload_encode(SilcUInt16 id_len,
                                               const unsigned char *id,
                                               SilcUInt16 cipher_len,
                                               const unsigned char *cipher,
                                               SilcUInt16 key_len,
                                               const unsigned char *key);

    Encodes channel key payload into a buffer and returns it. This is used
    to add channel key payload into a packet.