On Non-Cooperative Location Privacy: A Game-Theoretic Analysis

In mobile networks, authentication is a required primitive for the majority of security protocols However, an adversary can track the location of mobile nodes by monitoring pseudonyms used for authentication A frequently proposed solution to protect location privacy suggests that mobile nodes collectively change their pseudonyms in regions called mix zones Because tins approach is costly, self-interested mobile nodes might decide not to cooperate and could thus jeopardize the achievable location privacy In this paper, we analyze the non-cooperative behavior of mobile nodes by using a game-theoretic model, where each player aims at maximizing its location privacy at a minimum cost We first analyze the Nash equilibria in n-player complete information games Because mobile nodes in a privacy-sensitive system do not know their opponents' payoffs, we then consider incomplete information games We establish that symmetric Bayesian-Nash equilibria exist with simple threshold strategies in n-player games and derive the equilibrium strategies By means of numerical results, we show that mobile nodes become selfish when the cost of changing pseudonyms is small, whereas they cooperate more when the cost of changing pseudonyms increases Finally, we design a protocol - the Pseudo Game protocol - based on the results of our analysis