Toward Achieving Location Privacy: A Game‐Theoretic and Mean‐Field Approach

Mohammad Hossein Manshaei



In many envisioned mobile ad hoc networks to disseminate information, nodes periodically beacon in order to advertise their presence. In this way, they can receive messages addressed to them or participate in routing operations. Yet, these beacons leak information about the nodes and their users and thus hamper their privacy. A classical remedy consists in each node making use of (certified) pseudonyms and changing its pseudonym in specific locations called mix zones. Of course, privacy is then higher if the pseudonyms are short‐lived (i.e., nodes have a short distance‐to‐confusion), but pseudonyms can be costly, as they are usually obtained from an external authority. Due to the associated costs, self‐interested mobile nodes might decide not to cooperate and could thus jeopardize the achievable location privacy. In this talk, we first analyze the non‐cooperative behavior of mobile nodes with a game‐theoretic model, where each player aims at maximizing its location privacy at a minimum cost. 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 behave in a selfish manner when the cost of changing pseudonym is small, whereas they cooperate more when the cost of changing pseudonym increases. We then design a mix‐zone protocol ‐ the PseudoGame protocol ‐ based on the results of our analysis [1]. This work is a part of the recent trend of blending game theory with security/cryptographic mechanisms when selfish parties are involved [2]. In the second part of the talk, using a mean field approach, we provide a detailed analytical evaluation of the age of pseudonyms when mobile nodes use mix zones. We corroborate our model by a set of simulations. We provide a detailed quantitative framework for selecting the parameters of a pseudonym‐based privacy system in peer‐to‐peer wireless networks [3]. References: [1] J. Freudiger, M. H. Manshaei, J.‐P. Hubaux, and D. C. Parkes, “On Non‐cooperative Location Privacy: A Game‐theoretic Analysis,” In ACM Conference on Computer and Communications Security (CCS), 2009. [2] Security Games in Computer Networks: [3] J. Freudiger, M. H. Manshaei, J.‐Y. Le Boudec, and J.‐P. Hubaux, “On the Age of Pseudonyms in Mobile Ad Hoc Networks,” In IEEE Infocom, 2010. Short Bio: Mohammad Hossein Manshaei is a senior researcher and lecturer at EPFL, Switzerland. He earned his Ph.D. in computer science and distributed systems from the University of Nice Sophia‐Antipolis, France, in 2005. He completed his thesis work at INRIA Sophia‐Antipolis. He earned his B.Sc. degree in electrical engineering and his M.Sc. degree in communication engineering from the Isfahan University of Technology (IUT), Iran, in 1997 and 2000, respectively. His research interests include wireless networking, game theory, wireless security and privacy, and cognitive radios.

[Mohammad Hossein Manshaei]