Towards approximate opacity of cyber-physical system: WIP abstract

Opacity is an important information-flow security property in the analysis of cyber-physical systems. In this abstract, we extend the concept of opacity to systems whose output sets are equipped with metrics. A new concept called approximate opacity is proposed in order to quantitatively evaluate the security guarantee level with respect to the measurement precision of the intruder. Then we propose a new simulation-type relation called approximate opacity preserving simulation relations, which characterizes how close two systems are in terms of the satisfaction of approximate opacity. We also discuss how to construct approximate opacity preserving symbolic models for a class of discrete-time control systems.