A comprehensive review on blockchains for Internet of Vehicles: Challenges and directions

Internet of Vehicles (IoVs) consists of smart vehicles, Autonomous Vehicles (AVs) as well as roadside units (RSUs) that communicate wirelessly to provide enhanced transportation services such as improved traffic efficiency and reduced traffic congestion and accidents. Unfortunately, current IoV networks suffer from security, privacy, and trust issues. Blockchain technology emerged as a decentralized approach for enhanced security without depending on trusted third parties to run services. Blockchain offers the benefits of trustworthiness and immutability and mitigates the problem of a single point of failure and other attacks. In this work, we present the state-of-the-art Blockchain-enabled IoVs (BIoVs) with a particular focus on their applications, such as crowdsourcing-based applications, energy trading, traffic congestion reduction, collision, accident avoidance, infotainment, and content caching. We also present in-depth applications of federated learning (FL) for BIoVs. The key challenges of integrating Blockchain with IoV are investigated in several domains, such as edge computing, machine learning, and Federated Learning (FL). Lastly, we present several open issues, challenges, and future opportunities in AI-enabled BIoV, hardware-assisted security for BIoV, and quantum computing attacks on BIoV applications.