Symbolic Timed Observational Equivalence

TL;DR

This paper introduces a new symbolic timed observational equivalence to detect time side channels in systems, enabling automated verification of whether systems are distinguishable based on timing information using SMT-solvers.

Contribution

It proposes a novel definition of timed observational equivalence that incorporates time side channels and leverages symbolic time constraints for automation.

Findings

Defines a new timed observational equivalence

Uses SMT-solvers for automated analysis

Enhances system distinguishability verification

Abstract

Intruders can infer properties of a system by measuring the time it takes for the system to respond to some request of a given protocol, that is, by exploiting time side channels. These properties may help intruders distinguish whether a system is a honeypot or concrete system helping him avoid defense mechanisms, or track a user among others violating his privacy. Observational equivalence is the technical machinery used for verifying whether two systems are distinguishable. Moreover, efficient symbolic methods have been developed for automating the check of observational equivalence of systems. This paper introduces a novel definition of timed observational equivalence which also distinguishes systems according to their time side channels. Moreover, as our definition uses symbolic time constraints, it can be automated by using SMT-solvers.