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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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International audienceIn this paper, we propose a distributed and dynamic public key infrastructure for vehicular ad hoc networks. We aim to achieve the fundamental security requirements, particularly the authentication, the confidentiality, and a reliable vehicle-to-vehicle data exchange. To make the certification authority (CA) reachable by all vehicles, we distribute its role among a set of dynamically elected vehicles. The election of dynamic CAs is based on a clustering algorithm where the cluster heads will be CAs in their clusters. The cluster heads are elected following two criteria: security and mobility. Due to the important role of the CA in each cluster and to protect it from DOS attacks, we introduce a VANETs dynamic demilitarized zone for vehicular ad hoc networks. Its role is to handle the certification requests sent to the CA from unknown vehicles, and hence, it avoids compromising it. Additionally, we detail the certificates management in the proposed public key infrastructure, and we propose a mechanism to provide anonymous vehicle-to-vehicle communications using pseudonyms. To study the feasibility of our distributed architecture and particularly the clustering algorithm, we propose a probabilistic model considering the speed of vehicles and taking into account the safety distance between vehicles. We carried out a set of simulations to evaluate the performance of the proposed clustering algorithm in both urban and highway environments. Hence, we study the effects of the transmission range, the speed of vehicles, and the number of trusted vehicles in the network on the stability and the efficiency of the overall proposed architecture. We also study some delays characterizing the certificates management. Our simulation results show that the security of the proposed architecture closely depends on the number of trusted vehicles in the network, and the stability depends on the mobility of vehicles on the road and on the total number of trusted vehicles

International audienceIn this paper, we propose a secure and distributed public key infrastructure for VANETs. It is based on an hybrid trust model which is used to determine the trust metric (Tm) of vehicles. It consists on a monitoring system processing on two aspects: the cooperation of vehicles and the legitimacy of the broadcasted data. We propose a fuzzy-based solution in order to decide about the honesty of vehicles. Then, the vehicles which are trusted (Tm = 1), also, they have at least one trusted neighbor can candidate to serve as certification authorities CAs in their clusters. In order to increase the stability of our distributed architecture, the CA candidate which has the lowest relative mobility will be elected as certification authority CA. A set of simulations is conducted. We evaluate particularly the efficiency and the stability of the clustering algorithm as a function of the speed, the average number of vehicles on the platoon and the percentage of trusted vehicles

Vehicular Ad hoc Networks (VANETs) are one of the pillars of the Internet of Vehicles, they provide plenty of applications ranging from safety to entertainment. Safety applications largely depend on reliable and authentic traffic-related data. However, ensuring the data reliability and authenticity is facing many challenges due mainly to the scalability of VANETs such as the high speed, the long roads, and the open nature of VANETs. This paper addresses these challenges by proposing a decentralized Blockchain-based trust management framework (BC-TMF) aiming to compute trust metrics for vehicles. These trust metrics rely on the authenticity of the messages. Each vehicle assesses the authenticity of the received messages in real-time, calculates a local trust metric for the originator of such messages, then shares it with a miner. Periodically each miner aggregates the received trust metrics into global trust metrics, then packs them in a block. To investigate the efficiency and consistency of the proposed framework, extensive simulations are conducted. The obtained results show that the proposed BC-TMF has an excellent capability in computing accurate trust metrics for vehicles. Besides, it outperforms the existing ones in terms of the accuracy of computed trust metrics, particularly for malicious vehicles.

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