Covert timing channel capacity of rate monotonic real-time scheduling algorithm in MLS systems

Real-time systems must satisfy timing constraints. In our previous work, we showed that a covert timing channel cannot be completely closed in some system configurations due to the timing constraints imposed by the RateMonotonic (RM) real-time scheduling algorithm. In this paper, we construct a probabilistic model to measure two quantities of a covert timing channel in RM based systems: channel capacity and quantity of specific information. We show how these two metrics can be calculated from our probabilistic model and why they are useful metrics in evaluation of a covert (timing) channel.