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International audienceIn this paper we propose a trust model based on a Markov chain in order to formalize the trust metric variation and its stability in the context of Vehicular Ad hoc Networks (VANETs). The proposed model takes into account not only the dynamic trust metric variation according to the vehicles behaviors, but also the constraints related to the monitoring process. In our model each vehicle can act as monitor and update the trust metric of its neighbors according to their behavior in the network. In addition, our model can be customized through different parameters like the trust interval and the number of transitions needed to reach the highest trust level. This flexibility enables to adapt the model according to the application context. The performance evaluation of the proposed model is presented with different parameters and two types of disruptive vehicles are taken into account: malicious and selfish. The obtained results show the resistance, the robustness and the incentive of the proposed model against the fluctuations of the vehicles behaviors

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Abstract. In this paper, we propose a new architecture based on an efficient trust model and clustering algorithm in order to distribute a certification authority (CA) for ensuring the distribution of certificates in each cluster. We use the combination of fully self-organized security for trust model like PGP adapted to ad-hoc technology and the clustering algorithm which is based on the use of trust and mobility metric, in order to select the clusterhead and to establish PKI in each cluster for authentication and exchange of data. Furthermore, we present new approach Dynamic Demilitarized Zone (DDMZ) to protect CA in each cluster. The principle idea of DDMZ consists to select the dispensable nodes, also called registration authorities; these nodes must be confident and located at one-hope from the CA. Their roles are to receive, filter and treat the requests from any unknown node to CA. With this approach, we can avoid the single point of failure in each cluster. This architecture can be easily extended to other hierarchical routing protocols. Simulation results confirm that our architecture is scalable and secure.