Design of a Two Layered Blockchain-Based Reputation System in Vehicular Networks

Vehicles on the road, where an Intelligent Transportation System (ITS) is built, can share a lot of traffic information and drive more safely and efficiently through data sharing. Since incorrect information misleads vehicles and causes confusion in traffic, a vehicular trust model is needed to check the message’s trustworthiness while considering the vehicle’s properties and protecting its privacy. In this paper, we proposed a two layered blockchain-based reputation system, which consists of a local one-day message blockchain and a global vehicle reputation blockchain. It can administrate the reputation score securely and preserve the vehicle’s partial privacy. The proposed model efficiently manages local traffic information through the local one-day blockchain, reducing the memory overhead of vehicles. As the vehicle’s actual identity and activities in other areas are hidden by using one-time public keys, partial privacy of the vehicle is preserved. According to the activity of the vehicle, the vehicle’s reputation score is updated and stored permanently in the global reputation blockchain. We also suggested the location-based practical byzantine fault tolerance (LPBFT), a new consensus algorithm for fast block generating. The LPBFT lowers message propagation time through location-based primary node selection and is about 1.4 times faster than existing PBFT. The simulation results show the efficiency and the feasibility of LPBFT and our proposed protocol.