Synthesis of covert actuator and sensor attackers

Abstract

In this work, we shall investigate the problem of covert attacker synthesis in the framework of supervisory control of discrete-event systems. Intuitively, the covertness property says that the attacker cannot reach a situation where its existence has been detected by the supervisor while no damage can be caused. We consider covert attackers that can exercise both actuator attacks (including enablement attacks and disablement attacks) and sensor attacks (restricted to sensor replacement attacks), where the (partial-observation) attackers may or may not eavesdrop the control commands issued by the supervisor. We shall develop an exponential time reduction from the covert attacker synthesis problem to the well studied Ramadge–Wonham supervisor synthesis problem, which generalizes our previous work on a reduction based approach for covert actuator attacker synthesis, for both the damage-reachable goal and the damage-nonblocking goal. We also provide discussions on conditions under which the exponential blowup in state sizes, due to the reduction construction, can be avoided.