SilcSKEStatus silc_ske_responder_finish(SilcSKE ske,
                                            SilcPublicKey public_key,
                                            SilcPrivateKey private_key,
                                            SilcSKEPKType pk_type);

    This function finishes the responder's SKE session, and this function
    is called either immediately, or with short timeout, after the
    silc_ske_responder_phase_2 returned. This will send our reply to
    the initiator.  The caller must provide the caller's public key and
    private key as argument, since the public key is sent to the responder,
    and the private key is be used to generate digital signature.

    After this function the application must wait for the end indication
    from the intiator, and when it is received the silc_ske_end is called.