# Secure Trust-Based Blockchain Architecture to Prevent Attacks in VANET
## 7 Conclusions  
VANETs have received an enormous amount of attention from both researchers and the vehicular industry due to their potential in delivering information to provide safety and infotainment messages to drivers and passengers. Unfortunately, trust management for vehicles is still an open issue in VANETs. Therefore, this research proposed a secure trust-based blockchain architecture to effectively mitigate several network attacks while preserving the privacy and security of the users in VANET. The proposed solution was developed to mitigate networks attacks, such as message fabrication, impersonation, DoS attacks, and Sybil attacks, while maintaining the privacy of the users in VANET. The blockchain technology in the proposed solution uses timestamps and hashing techniques to maintain the freshness of the messages delivered. These techniques minimize message fabrication or modification attacks, as the timestamps record the time a message is delivered, while hashing secures the message against tampering by malicious nodes. Furthermore, the proposed solution also uses a message rating and credibility approach via the blockchain technology. The message rating and credibility approach ensures trust management among vehicles during information exchange in VANET. Any vehicle that communicates fake messages to other vehicles in the network will be rated with low values, decreasing its credibility. Vehicles with a lower trust value than the threshold value will be rejected from the network and their vehicle certificates will be revoked. The performance of the proposed solution was evaluated via simulation using the Veins simulation tool under two settings, which were without denial of service attacks and with denial of service attacks. From the simulation, the proposed solution was found to perform better than the benchmark algorithms in terms of the PDR against increasing number of nodes in the network. The simulations showed that  
Figure 21: Percentage of throughput with the secure-geographical routing protocol greedy perimeter stateless routing (S-GPSR) protocol.  
the proposed solution experienced up to 98% of PDR when there were no attacks launched in the network, while during attack, the proposed solution incurred up to 94% of PDR. Interestingly, the proposed solution experienced a similar delay of 0.130 s over increasing number of vehicles in the network, with and without network attacks. Despite the improved performance of the proposed solution, this study was still bound to several research limitations. First, the proposed solution was only implemented and evaluated on one component of the intelligent transportation system--vehicular ad hoc network (ITS--VANET). Future works should include deployment of the proposed solution in autonomous vehicles and deployment in a multi-junction road network. Cooperative-ITS (C-ITS) is another component of ITS that supports connectivity [47] and cooperative awareness of road users, which can be achieved with regular exchange of safety information among users [48]. In the future, C-ITS will be a possible application to be integrated with the proposed solution and to investigate the performance of the proposed solution in enabling cooperative awareness in VANET.  
Conceptualization, A.S.K.; Methodology, A.S.K. and S.T.; Software, Y.J.; Validation, K.B. and Y.J.; Formal Analysis, Y.J.; Investigation, K.B., S.T. and J.A.; Resources, A.S.K.; Data Curation, K.B.; Writing-Original Draft Preparation, K.B.; Writing-Review & Editing, A.S.K., Y.J. and S.T.; Visualization, K.B.; Supervision, A.S.K.; Project Administration, J.A.; Funding Acquisition, A.S.K and Y.J. The authors would like to thank Research Innovation & Enterprise Centre (RIEC), Centre of Graduate Studies (CGS) of University Malaysia Sarawak (UNIMAS) and Prince Sultan University, Riyadh, Kingdom of Saudi Arabia for their continuous support towards the development of this research. This Research work is carried out under the Project ID F08/PGRG/1908/2019. The authors declare no conflict of interest.