Opacity Generalised to Transition Systems

Recently, opacity has proved a promising technique for describing security properties. Much of the work has been couched in terms of Petri nets. Here, we extend the notion of opacity to the model of labelled transition systems and generalise opacity in order to better represent concepts from the literature on information flow. In particular, we establish links between opacity and the information flow concepts of anonymity and non-inference. We also investigate ways of verifying opacity when working with Petri nets. Our work is illustrated by an example modelling requirements upon a simple voting system.