A framework for current-state opacity under dynamic information release mechanism. (June 2022)

• Record Type: Journal Article
• Authors: Hou, Junyao; Yin, Xiang; Li, Shaoyuan
• Is Part Of: Automatica. Volume 140(2022)
• Publication Date: 2022-06
• Subjects: Opacity -- Discrete-event systems -- Security -- Information release; Automatic control -- Periodicals; Automation -- Periodicals; 629.805
• DOI: 10.1016/j.automatica.2022.110238
• Languages: English
• ISSNs: 0005-1098

Abstract

Abstract: Opacity is an important information-flow security property that characterizes the plausible deniability of a dynamic system for its "secret" against eavesdropping attacks. As an information-flow property, the underlying observation model is the key in the modeling and analysis of opacity. In this paper, we investigate the verification of current-state opacity for discrete-event systems under Orwellian-type observations, i.e., the system is allowed to re-interpret the observation of an event based on its future suffix. First, we propose a new Orwellian-type observation model called the dynamic information release mechanism (DIRM). In the DIRM, when to release previous "hold on" events is state-dependent. Then we propose a new definition of opacity based on the notion of history-equivalence rather than the standard projection-equivalence. This definition is more suitable for observations that are not prefix-closed. Finally, we show that by constructing a new structure called the DIRM-observer, current-state opacity can be effectively verified under the DIRM. Computational complexity analysis as well as illustrative examples for the proposed approach is also provided. Compared with the existing Orwellian-type observation model, the proposed framework is more general in the sense that the information-release-mechanism is state-dependent, information is partially released and the corresponding definition of opacity is more suitable for non-prefix-closed observations.