SilcBool silc_client_send_private_message(SilcClient client,
                                              SilcClientConnection conn,
                                              SilcClientEntry client_entry,
                                              SilcMessageFlags flags,
                                              SilcHash hash,
                                              unsigned char *data,
                                              SilcUInt32 data_len);

    Sends private message to remote client. If private message key has
    not been set with this client then the message will be encrypted using
    the session keys used in `conn' connection.  If the `flags' includes
    SILC_MESSAGE_FLAG_SIGNED the message will be digitally signed with the
    SILC key pair associated with `conn'.  In this case the caller must also
    provide the `hash' pointer.

    Returns TRUE if the message was sent, and FALSE if error occurred.
    This function is thread safe and private messages can be sent from
    multiple threads.