Blockchain-Empowered Content Cache System for Vehicle Edge Computing Networks

Content cache for Vehicle Edge Computing (VEC) Network is a promising service to reduce transmission delay and cost. Existing content cache system requires Road Side Units (RSUs) to participate in the content transmission process, however, RSUs are usually distributed along the road without strong security protection, which is vulnerable to being compromised by attackers. In this way, the cached content is vulnerable to tamper and the widespread dissemination of malicious content will bring a devastating blow to the trust mechanism of the caching system. In this paper, we propose a Blockchain-empowered content cache system, where the content index (containing the provider's address, the hash value of the content) is adopted to guarantee the validity of the content. The content index is deposited in the Blockchain system, the immutability and distributed architecture of Blockchain can effectively prevent the content index from being tampered. However, such tamperresistance property comes at the cost of a long confirmation caused by the consensus process. A time-oriented Proof of Work (PoW) consensus algorithm is proposed to improve the Blockchain efficiency. And a local indexing set-based search mechanism is established to reduce the long search delay caused by the chain-based structure. Moreover, the simulation results also demonstrate that the Blockchain-empowered cache system can improve the hit ratio of servers by providing customized request information.