a security system that is useful for protecting vehicles from theft and buildings from unauthorized entry , for example , includes utilizing random numbers within remotely transmitted signals . a remote signaling device transmits a signal to a system controller with instructions for a desired operation of the system . the invention prevents a potential thief from capturing one or more transmitted signals and later mimicking or predicting a subsequent signal by including or utilizing a random number when generating the transmitted signal . the random number is incorporated into the transmitted signal in one of several ways according to this invention . single - use or limited re - use of random numbers enhances the security and integrity of the system .