Tracking Games in Mobile Networks

Users of mobile networks can change their identifier in regions called mix zones in order to defeat the tracking of their location by third parties. Mix zones must be carefully deployed in the network to reduce the cost induced on mobile users and to provide high location privacy. Unlike most previous work that considers a global adversary, we consider a local adversary equipped with multiple eavesdropping stations. We study the interaction between the local adversary deploying eavesdropping stations to track mobile users and mobile users deploying mix zones to protect their location privacy. We use a game-theoretic model to predict the strategies of both players. We derive the strategies at equilibrium in complete and incomplete information scenarios and propose an algorithm to converge to the equilibrium. Finally, based on real road traffic information, we numerically quantify the effect of complete and incomplete information on the strategies of mobile users and of the adversary. In complete information scenarios, mobile users and the adversary tend to adopt complementary strategies: users place mix zones where there is no eavesdropping station, and vice versa. In incomplete information scenarios, the location privacy level achieved by mobile users depends on their level of uncertainty about the strategy of the adversary.