BlockchainEmpowered 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 Blockchainempowered content cache system, where the content index (containing the providerxe2x80x99s 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 timeoriented Proof of Work (PoW) consensus algorithm is proposed to improve the Blockchain efficiency. And a local indexing setbased search mechanism is established to reduce the long search delay caused by the chainbased structure. Moreover, the simulation results also demonstrate that the Blockchainempowered cache system can improve the hit ratio of servers by providing customized request information.

Blockchain Applied to Vehicular Odometers Fraud in automobile odometers is a billion dollar problem worldwide. The technical requirements behind any solution for this problem go through the perennial, secure, and immutable registration of vehicular data. Such requirements immediately raise the question of how blockchain technology could be used for this purpose. In this article, the requirements, design choices, and construction details of a blockchain architecture for vehicular odometers are presented and discussed. The architecture advances the state of the art by adopting a more efficient consensus algorithm than the traditional ones, such as proof of work. Results from a prototype proof ofconcept of the proposed architecture validate the solution, which is able to validate a new block in the blockchain every two seconds. Applicability in real scenarios is one step ahead and very promising.