1 research outputs found
Reduced-Complexity Verification for K-Step and Infinite-Step Opacity in Discrete Event Systems
Opacity is a property that captures security concerns in cyber-physical
systems and its verification plays a significant role. This paper investigates
the verifications of K-step and infinite-step weak and strong opacity for
partially observed nondeterministic finite state automata. K-step weak opacity
is checked by constructing, for some states in the observer, appropriate
state-trees, to propose a necessary and sufficient condition. Based on the
relation between K-step weak and infinite-step weak opacity, a condition that
determines when a system is not infinite-step weak opaque is presented.
Regarding K-step and infinite-step strong opacity, we develop a secret-involved
projected automaton, based on which we construct secret-unvisited state trees
to derive a necessary and sufficient condition for K-step strong opacity.
Furthermore, an algorithm is reported to compute a verifier that can be used to
obtain a necessary and sufficient condition for infinite-step strong opacity.
It is argued that, in some particular cases, the proposed methods achieve
reduced complexity compared with the state of the art