Opacity Generalised to Transition Systems

Abstract

Abstract. Recently, opacity has proved to be a promising technique for describing security properties. Much of the work has been couched in terms of Petri nets. Here, we extend the notion of opacity to the model of labelled transition systems and generalise opacity in order to better represent concepts from the work on information flow. In particular, we establish links between opacity and the information flow concepts of anonymity and non-interference such as non-inference. We also investigate ways of verifying opacity when working with Petri nets. Our work is illustrated by an example modelling requirements upon a simple voting system.

Opacity with powerful attackers

“…Opacity has been addressed in several settings since the work of Bryans et al (2005) and Badouel et al (2007). Our approach does not only consist of checking whether opacity holds, but also provides the means to control a system in such a way that observed traces are not sufficient to decide whether the current state of the system is a secret one.…”

“…However, the properties to protect are not always definable in terms of occurrences of actions from a given subset. A larger setting called opacity has been proposed (Bryans et al, 2005) to consider hiding more general properties of runs. This notion formalizes the absence of information flow or, more precisely, the impossibility for an attacker to infer the truth of a predicate φ (it could be the occurrence in the system of some particular sequences of events, or the fact that the system is in some particular secret configuration).…”

Unifying Hyper and Epistemic Temporal Logics

“…These mechanisms are required to formally express information-flow security properties which specify how information may propagate from inputs to outputs, such as non-interference [12] or opacity [5]. In the literature, two powerful temporal logic formalisms have been proposed for expressing such security requirements that, in general, go beyond regular properties.…”

Opacity of discrete event systems and its applications

“…Secrecy has been studied before, for example, in [1] [5] [2] [6] [22]. In [2], for a finite state system with partial observers and for each observer, a secret is defined as a subset of trajectories.…”

“…This work is further extended in [12] [26]. In [6], the notion of opacity (secrecy in our term) is generalized to labeled transition systems. Links between secrecy and the information flow concepts of anonymity and non-inference are established.…”