An Epistemic Logic Based Framework for Reasoning about Information Hiding

The last ten years witnessed a sustained effort aimed at developing a formalism appropriate for rigorous reasoning about information hiding related properties. Among the various existent proposals one can distinguish the highly general approach of Halpern and O´Neil that employs a simple epistemic logic in the context of a multi-agent system. Still, in the context of the same formalism, basic concepts like unlink ability, undetectability, unobservability or pseudonymity are very scarcely discussed in the literature. The goal of this paper is to fill this gap by using the same epistemic logic based framework. Here we extend the aforementioned formalism to include group epistemic operators (everyone knows, common knowledge and distributed knowledge) and prove that the inference system that is thus obtained is compatible with the S5 axiomatic system and the conjunctivity axiom. We propose epistemic formalizations not only for anonymity (Halpern and O´Neil), privacy, onymity and identity (Tsukada et al.) but also for a wide spectrum of information hiding related concepts: protocol, (un) link ability, (un) traceability, (un) detectability, (un) identifiability, unobservability, pseudonymity, dissimulation. To provide an overview, we organize a large number of terms related to computer security in a comprehensive hierarchical structure divided in three sections: setting, ends and means. Basic properties and relationships between these concepts are also provided.