void
    silc_client_perform_key_agreement(SilcClient client,
                                      SilcClientConnection conn,
                                      SilcClientEntry client_entry,
                                      char *hostname,
                                      int port,
                                      SilcKeyAgreementCallback completion,
                                      void *context);

    Performs the actual key agreement protocol. Application may use this
    to initiate the key agreement protocol. This can be called for example
    after the application has received the `key_agreement' client operation,
    and did not return TRUE from it.

    The `hostname' is the remote hostname (or IP address) and the `port'
    is the remote port. The `completion' callback with the `context' will
    be called after the key agreement protocol.

    NOTE: If the application returns TRUE in the `key_agreement' client
    operation the library will automatically start the key agreement. In this
    case the application must not call this function. However, application
    may choose to just ignore the `key_agreement' client operation (and
    merely just print information about it on the screen) and call this
    function when the user whishes to do so (by, for example, giving some
    specific command). Thus, the API provides both, automatic and manual
    initiation of the key agreement. Calling this function is the manual
    initiation and returning TRUE in the `key_agreement' client operation
    is the automatic initiation.