POSTER: A Common Framework for Resilient and Safe Cyber-Physical System Design.

Cyber-physical systems (CPS), which are often required to satisfy critical properties such as safety, have been shown to be vulnerable to exploits originating from cyber and/or physical sides. Recently, novel resilient architectures, which equip CPS with capabilities of recovering to normal operations, have been developed to guarantee the safety of CPS under cyber attacks. These resilient architectures utilize distinct mechanisms involving different parameters and are seemingly unrelated. Currently, the analysis and design methods of one novel resilient architecture for CPS are not readily applicable to one another. Consequently, evaluating the appropriateness and effectiveness of a set of candidate resilient architectures to a given CPS is currently impractical. In this poster, we report our progress on the development of a common framework for analyzing the safety and assessing recovery performance of two or more resilient architectures intended for CPS under attacks. We formulate a hybrid model as a common representation of resilient architectures. Our insight is that the resilient architectures have a shared set of discrete states, including vulnerable, under attack, unsafe, and recovery modes, which can be mapped to the discrete states of the unifying hybrid model. The hybrid model enables a unified safety analysis. We parameterize the required behaviors for the cyber and physical components in order to guarantee safety. The parameters then inform the development of metrics to measure the resilience of CPS. For CPS consisting of multiple heterogeneous components, we show that the effect of interconnections on the spatial and temporal parameters can be quantified efficiently, allowing a compositional approach to the safety verification of large-scale CPS.