  Opacity, an information-flow property related to the privacy and security of
a system, has been extensively studied in the context of discrete event
systems. Although various notions of opacity have been proposed, in all cases
the considered secret was constant. This work focuses on current-state opacity,
considering a scenario where the secret changes dynamically with the system
evolution. In other words, we propose the new notion of generalized
current-state opacity (GCSO), which is with respect to a dynamic-secret model
rather than a constant secret. Moreover, we provide a method to verify GCSO
based on the construction of the GCSO-verifier. Finally, a practical example is
given to illustrate the proposed notion and the method for its verification.
