A new approach for the verification of infinite-step and -step opacity using two-way observers

• Autores: Xiong Yin, Stéphane Lafortune
• Localización: Automatica: A journal of IFAC the International Federation of Automatic Control, ISSN 0005-1098, Vol. 80, 2017, págs. 162-171
• Idioma: inglés
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• Resumen

  • Abstract In the context of security analysis for information flow properties, where a potentially malicious observer (intruder) tracks the observed behavior of a given system, infinite-step opacity (respectively, K -step opacity) holds if the intruder can never determine for sure that the system was in a secret state for any instant within infinite steps (respectively, K steps) prior to that particular instant. We present new algorithms for the verification of the properties of infinite-step opacity and K -step opacity for partially-observed discrete event systems modeled as finite-state automata. Our new algorithms are based on a novel separation principle for state estimates that characterizes the information dependence in opacity verification problems, and they have lower computational complexity than previously-proposed ones in the literature. Specifically, we propose a new information structure, called the two-way observer, that is used for the verification of infinite-step and K -step opacity. Based on the two-way observer, a new upper bound for the delay in K -step opacity is derived, which also improves previously-known results.