An Epistemic Logic Based Framework for Reasoning about Information Hiding

Abstract

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 unlinkability, 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)linkability, (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.

Compiling an Epistemic Logic for Multiagent Systems

“…Continuing in Ref. the line of research started by Halpern and O'Neill in Ref. and and further developed by Tsukada et al., we found it very difficult to formally express that a certain agent considers a fact to be true whereas the same fact is not actually true at the system level.…”

“…This article answers the questions that were addressed there and to sum up the core of the epistemic logic used in Ref. to formally express all the main definitions in Ref. .…”

“…During the presentation of Ref. at ARES 2011 conference, the main interest was related to the complementarity between the behavioral equivalence, defined in the referenced paper and the observational equivalence presented in Refs. and .…”

On compositional reasoning about anonymity and privacy in epistemic logic

“…Consequently, in these systems, there exist some pairs comprising an agent i and an action submit(c) such that they are not role interchangeable. Cases 8,9,10,and 11 in Table 1 are respectively derived from Cases 2, 3, 4, and 5 by replacing "up-to" anonymity/privacy properties with minimal anonymity/privacy properties. There are two problems in obtaining these derivations.…”

On the limits of provable anonymity

“…Several works use logic based approach, which simplifies the cryptographic properties [19,20,22,33,35].…”