Mix-Zones for Location Privacy in Vehicular Networks

Vehicular Networks (VNs) seek to provide, among other applications, safer driving conditions. To do so, vehicles need to periodically broadcast safety messages providing precise position information to nearby vehicles. However, this frequent messaging (e.g., every 100 to 300ms per car) greatly facilitates the tracking of vehicles, as it suffices to eavesdrop the wireless medium. As a result, the drivers privacy is at stake. In order to mitigate this threat, while complying with the safety requirements of VNs, we suggest the creation of mix-zones at appropriate places of the VN. We propose to do so with the use of cryptography, and study analytically how the combination of mix-zones into mix-networks brings forth location privacy in VNs. Finally, we show by simulations that the proposed mix system is effective in various scenarios

Mentoring talent in IT security -A case study

Abstract Talent management is usually not well-supported by traditional curricula, because university courses are typically designed for a large number of average students and not for the few outstanding ones. In this paper, we share our experiences on running a talent mentoring program in IT security at our university. We describe the whole process from increasing awareness of IT security among students, via maintaining a community of practice where they can improve their skills, to finally connect them to well-established IT companies. We also introduce avatao, a platform to support hands-on IT security practice. Our methods could serve as a blueprint to establish a successful talent management program in IT security in a typical academic environment

Non-cooperative behavior in wireless networks

Existing cellular networks are centrally managed and require a tremendous initial investment. With the advancement of new wireless technologies, the operators of traditional networks have to face new competition. New technologies make it possible to provide wireless services with substantially less investment. There are two interdependent trends that enable this progress: the evolution of technology and the evolution of spectrum policy. These two trends point towards a more colorful landscape of wireless communication technologies. In particular, new wireless technologies enable users and small operators to deploy their own networks and to compete with the large network operators that run traditional wireless networks. Because the participants have an increased control over their devices, they might be tempted to adjust their devices in order to benefit more from the network. This selfish (i.e., non-cooperative) behavior can dramatically decrease the efficiency of the operation of the network or even paralyze it completely. In this thesis, we consider various aspects of non-cooperative resource management in wireless networks using the methods provided by game theory. In the first part of the thesis, we present a comprehensive tutorial on game theory to facilitate the understanding of this theory as a tool. To emphasize the appropriateness of game theory in wireless networking, we present a set of selected examples along with their game-theoretic formalization. In the second part of the thesis, we are concerned with the non-cooperative behavior of users. More precisely, we focus on ad hoc wireless networks and assume that users can alter the default programming of their communication devices to improve performance. First, we consider the problem of multi-radio channel allocation and show that a Nash equilibrium driven by the selfish behavior of users achieves load-balancing. We propose two algorithms, each based on a different set of available information, to achieve the characterized Nash equilibria. Furthermore, we discuss other properties such as efficiency, fairness and coalition-proofness. In the remainder of this second part, we focus on the fundamental problem of packet forwarding in ad hoc networks. In static networks, we prove that cooperative Nash equilibria exist, but the set of conditions that enable selfish participants to mutually forward each others' packets are very restrictive. We also show that in dynamic networks, mobility promotes cooperation. In the third part of the thesis, we model the non-cooperative behavior of wireless network operators. We assume that they make strategic decisions to maximize the performance of their network. We also assume that the networks of different operators mutually affect each other, hence we model the decisions as network operator games. First, we study the scenario of co-located sensor networks and show that the network operators can mutually increase the lifetime of their network by cooperating. We also show that cooperation in terms of sharing sinks is more beneficial than providing packet forwarding of their sensors only. Second, we focus on the pilot power control of cellular networks assumed to operate in a shared spectrum. We identify Nash equilibria for different parameter values in a single-stage game and show that the cooperative solution can be enforced in a repeated game. Third, we consider the coexistence of cellular networks along national borders. We show that the operators have an incentive to be strategic at their borders, or, in other words, to adjust the transmit power of their pilot signals. We show the efficiency of the Nash equilibria for different user densities. Finally, we extend the payoff function to include the cost of using high pilot powers and relate this extended game to the well-known Prisoner's Dilemma

Cooperative Packet Forwarding in Multi-Domain Sensor Networks

Sensor networks are large scale networks of low-power devices that collaborate in order to perform a given task. The sensors are limited in battery energy, capacity and computational power. In recent years, researchers have proposed several protocols for such sensor networks assuming that all sensors belong to the same authority. In this paper, we introduce the concept of multi-domain sensor networks that was, to the best of our knowledge, never considered before. We propose a game-theoretic model to investigate the impact of cooperation and show the conditions for which cooperation is the best strategy. 1

Nash Equilibria of Packet Forwarding Strategies in Wireless Ad Hoc Networks

In self-organizing ad hoc networks, all the networking functions rely on the contribution of the participants. As a basic example, nodes have to forward packets for each other in order to enable multihop communication. In recent years, incentive mechanisms have been proposed to give nodes incentive to cooperate, especially in packet forwarding. However, the need for these mechanisms was not formally justified. In this paper, we address the problem of whether cooperation can exist without incentive mechanisms. We propose a model based on game theory and graph theory to investigate equilibrium conditions of packet forwarding strategies. We prove theorems about the equilibrium conditions for both cooperative and noncooperative strategies. We perform simulations to estimate the probability that the conditions for a cooperative equilibrium hold in randomly generated network scenarios. As the problem is involved, we deliberately restrict ourselves to a static configuration. We conclude that in static ad hoc networks— where the relationships between the nodes are likely to be stable—cooperation needs to be encouraged