Co-engineering Safety and Security in Industrial Control Systems: A Formal Outlook

An increasing openness and interconnectedness of safety-critical industrial control systems makes them vulnerable to security attacks. Hence, we should establish the integrated approaches enabling safety-security co-engineering. Such approaches should support an analysis of interdependencies between the mechanisms required for safety and security assurance. In this paper, we demonstrate how formal modelling can facilitate reasoning about the impact of certain security solutions on safety and vise versa. We rely on modelling and refinement in Event-B to systematically uncover mutual interdependencies and the constraints that should be imposed on the system to guarantee its safety even in the presence of security attacks. The approach is illustrated by a case study – a battery charging system of an electric car.