SilcBool silc_packet_set_sid(SilcPacketStream stream, SilcUInt8 sid);

    Sets new Security ID to the packet stream indicated by `stream'.  This
    is called only if the IV Included property was set to the stream
    by calling silc_packet_stream_set_iv_included.  This function sets
    new Security ID to the stream which is then included in the ciphertext
    of a packet.  The `sid' must be 0 when it is set for the very first
    time and must be increased by one after each rekey.  This function must
    be called every time new keys are added to the stream after a rekey.

    If this function is called when the IV Included property has not been
    set to the stream the `sid' will be ignored.  Returns FALSE if the
    IV Included has not been set, TRUE otherwise.