Making greed work in mobile ad hoc networks

Countermeasures against node misbehavior and selfishness are mandatory requirements in mobile ad hoc networks. Selfishness that causes lack of node activity cannot be solved by classical security means that aim at verifying the correctness and integrity of an operation. In this paper we outline an original security mechanism (CORE) based on reputation that is used to enforce cooperation among the nodes of a MANET. We then investigate on its robustness using an original approach: we use game theory to model the interactions between the nodes of the ad hoc network and we focus on the strategy that a node can adopt during the network operation. As a first result, we obtained the guidelines that should be adopted when designing a cooperative security mechanism that enforces mobile nodes cooperation. Furthermore, we were able to show that when no countermeasures are taken against misbehaving nodes, network operation can be heavily jeopardized. We then showed that the CORE mechanism is compliant with guidelines provided by the game theoretic model and that, under certain conditions, it assures the cooperation of at least half of the nodes of a MANET