Semantics-Based Noninterference Assessment in Cyber-Physical Systems

Event-aware information flow security in cyber–physical systems (CPSs) emphasizes the correlation among events. Event-aware noninterference is a security property capable to describe such a correlation. In light of the event-aware noninterference assessment problem, system modeling is a common means, and many studies have been done on such a problem by using formal modeling tools, i.e., Petri nets (PNs), at present. However, classical PNs suffer from the lack of modeling for patterns with semantic sharing of events, which can be modeled by labeled PNs (LPNs). In this article, we present the concept of semantics-based noninterference for the CPSs modeled by LPNs and focus on the assessment problem of semantics-based noninterference properties represented by semantics-based strong nondeterministic noninterference (SNNI) and extended bisimulation SNNI (EBSNNI). To this end, we first give the formal definitions of semantics-based SNNI and EBSNNI. Then, we analyze the assessment mechanisms of them according to the characteristics of semantic sharing of events in LPNs. On this basis, we provide the semantics-based noninterference assessment method involving the coarse and fine assessments to reveal the event-aware security of CPSs. Finally, a case study is provided to explain the significance of our research and the effectiveness of our method.