SilcSKEStatus silc_ske_payload_start_encode(SilcSKE ske,
                                                SilcSKEStartPayload payload,
                                                SilcBuffer *return_buffer);

    Utility function used to encode Key Exchange Start Payload from the
    `payload' structure. The encoded buffer is returned into the
    `return_buffer' and the caller must free it.