  In this paper, we investigate the problem of synthesizing resilient
supervisors against combined actuator and sensor attacks, for the subclass of
cyber-physical systems that can be modelled as discrete-event systems. We
assume that the attackers can carry out actuator enablement and disablement
attacks as well as sensor replacement attacks. We consider both risky attackers
and covert attackers in the setup where the (partial-observation) attackers may
or may not eavesdrop the control commands (issued by the supervisor). A
constraint-based approach for the bounded synthesis of resilient supervisors is
developed, by reducing the problem to the Quantified Boolean Formulas (QBF)
problem. The bounded synthesis problem can then be solved either with a QBF
solver or with repeated calls to a propositional satisfiability (SAT) solver,
by employing maximally permissive attackers, which can be synthesized with the
existing partial-observation supervisor synthesis procedures, as counter
examples in the counter example guided inductive synthesis loop.
