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Blockchain Based Decentralized Applications & Trust Management for VANETs
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Decentralized vehicular Ad-hoc Networks (VANETs), a promising technology to improve the Intelligent Transportation System (ITSs), face severe lagging in actual deployment and its extensive usage due to major unresolved issues such as security, data reliability, user privacy, and safe routing protocols. To overcome these issues, there is an urge to identify a platform that best suits VANET's easy deployment and usage in a decentralized fashion. In this regard, blockchain has received much attention as an emerging technology to provide better security on data sharing among many participants without an intermediary. This thesis aims to investigate blockchain technology's capability to secure vehicular data and vehicular node trust scores over a tamper-proof decentralized ledger that guarantees security, immutability, and accountability in Peer-to-Peer (P2P) networks such as VANET.Firstly, we explore how to leverage blockchain technology to design a specific application in the domain of decentralized VANETs, such as ride-sharing. We analyze the decentralized architecture for this application using smart contracts, and through experiments, we evaluate the costs associated with it. This framework serves as a basis for our further study to solve more challenging research problems in the consensus algorithm. The choice of a consensus algorithm directly affects the performance of a blockchain-based system in terms of transaction confirmation delays. In a VANET based on blockchain, the Proof of Work (PoW) and Proof of Stake (PoS) consensus might not be the best selection due to resource constraints and unfairness, respectively. In an attempt to improve consensus in a VANET application based on blockchain, we present the design of a novel consensus mechanism named Proof Of Driving for our previously presented ride-sharing application. We demonstrated that POD clubbed with a real-time service standard score protocol efficiently optimizes the number of miner nodes. The extensive experimental and security analyses presented on proposed consensus and service standard protocols demonstrate the effectiveness, security, and feasibility of miner node selection. However, VANET is not secure as vehicular communication is critically vulnerable to several kinds of active and passive routing protocol attacks. The most severe attack in routing is the Black Hole attack, which deteriorates the network's performance by dropping or misusing the intercepted data packets without forwarding them to the correct destination. This greatly hinders the application availability. Hence in the final chapter of this thesis, we experiment by incorporating trust models in VANET routing protocols to achieve a more efficient packet forwarding process. The results showed an improved packet delivery ratio and throughput of the entire network. The trust model should be able to resist various attacks and preserve the privacy of vehicles simultaneously. Hence we presented how to leverage consortium blockchain to secure vehicles' trust scores and distribute node trust in a decentralized network more efficiently. We evaluated the trust score aggregation process by the authorized RSUs, the time consumed for consensus, and updated trust score distribution. The results showed that the blockchain-based trust management provides an effective trust model for VANETs with transparency, conditional anonymity, efficiency, and robustness while efficiently eliminates the black hole nodes.