Information Leakage Games: Exploring Information as a Utility Function

TL;DR

This paper introduces a game-theoretic framework modeling attacker and defender strategies in information leakage scenarios, with utility based on information leakage, addressing non-linear behaviors in privacy and security contexts.

Contribution

It establishes the foundations of information leakage games, incorporating non-linear utility functions, and distinguishes between QIF-games and DP-games for different privacy measures.

Findings

Formalizes attacker-defender interactions using information leakage as utility

Develops two types of games: QIF-games and DP-games for different privacy models

Provides a basis for designing optimal defense strategies against information leakage

Abstract

A common goal in the areas of secure information flow and privacy is to build effective defenses against unwanted leakage of information. To this end, one must be able to reason about potential attacks and their interplay with possible defenses. In this paper, we propose a game-theoretic framework to formalize strategies of attacker and defender in the context of information leakage, and provide a basis for developing optimal defense methods. A novelty of our games is that their utility is given by information leakage, which in some cases may behave in a non-linear way. This causes a significant deviation from classic game theory, in which utility functions are linear with respect to players' strategies. Hence, a key contribution of this paper is the establishment of the foundations of information leakage games. We consider two kinds of games, depending on the notion of leakage considered. The first kind, the QIF-games, is tailored for the theory of quantitative information flow (QIF). The second one, the DP-games, corresponds to differential privacy (DP).