SilcBool
    silc_client_add_private_message_key_ske(SilcClient client,
                                            SilcClientConnection conn,
                                            SilcClientEntry client_entry,
                                            const char *cipher,
                                            const char *hmac,
                                            SilcSKEKeyMaterial key);

    Same as silc_client_add_private_message_key but takes the key material
    from the SKE key material structure.  This structure is received if
    the application uses the silc_client_send_key_agreement to negotiate
    the key material.  The `cipher' and `hmac' SHOULD be provided as it is
    negotiated also in the SKE protocol.