Abstract:

The Vehicular Ad-hoc NETworks (VANET) is a special Mobile Ad-hoc NETworks (MANET) with vehicles as nodes which have high mobility.The vehicles interact with each other through the network to achieve massive data sharing,so as to improve the transportation efficiency and safety of the Intelligent Transportation System (ITS).However,the existence of malicious vehicles brings serious security risks to the VANET and even to the entire transportation system.To address this problem,an improved Three Valued Subjective Logic (3VSL) algorithm is proposed to evaluate the reputation value of vehicles and identify malicious vehicles using reputation thresholds,and the trusted route search algorithm is used to improve the calculation accuracy.The method uses blockchain technology to store the trust database in a distributed manner,and at the same time guarantees the immutability of the data.It periodically updates the vehicle reputation value by combining the historical periodic reputation value of vehicle nodes,historical interaction information,and interaction frequency.In addition,the depth-first search (DFS) algorithm is used to determine the trust path between vehicles more precisely,and the six-degree spatial separation theory is used to solve the problem of low information due to the long trust path,and reputation thresholds are set to filter trust paths with a low information volume,which further improves the computational accuracy.Simulation results show that,compared with the traditional algorithms,the proposed algorithm has a significant improvement in the identification efficiency of malicious vehicles,and shows a good anti-attack performance in the face of group collusion attacks and On-off attacks.

Key words: vehicular ad-hoc networks, blockchain, trust management, three valued subjective logic