A noninterference model and hidden channels

We consider mathematical models of secure systems, namely, the traditional non-interference model and a probabilistic non-interference model. We demonstrate that a system can satisfy the conditions of the traditional non-interference model in presence of a subliminal channel from the high-security domain to the low-security one. We give a sufficient condition for absence of a system of subliminal channels in the automaton model.
This research was supported by the Russian Foundation for Basic Research, grant 01–01–00895.