Assessment of Multilevel Intransitive Non-Interference for Discrete Event Systems

Privacy of distributed cyber-physical systems can be compromised by the presence of information leaks which permit to external intruders to infer the state of the system itself. These systems are built using several off-the-shelf components with communication capabilities that provide a significant level of control, and lower operational costs in comparison to the traditional vendor-specific proprietary and closed-source systems. However, these components expose the control systems to more vulnerabilities and threats. This work focuses on the multi-level intransitive non-interference, a property particularly suitable to tackle privacy problems of control systems under attack. The property is characterized and verified using Petri net models and mathematical programming.