Research And Implementation Of Smart Contracts For Vehicle Chain

With the increasing number of smart cars and the concept of smart transportation,Internet of Vehicles（Io V）as its basic support technology has started to develop rapidly,but in the face of the increasing number of cars and massive data,the traditional Io V interaction model is inadequate in terms of key management,data storage,concurrency performance and response speed,and the centralized authentication and data storage methods are vulnerable to malicious attacks leading to single point of failure,identity forgery,data tampering and privacy leakage.To solve these problems,this thesis proposes a dualchain structured vehicle chain using the decentralized and anti-tampering characteristics of blockchain,focusing on the automatic operation of Io V business using smart contracts,with the main research content as follows.1.Dual-chain architecture of the vehicle chain model.After analyzing the problems of centralized Io V architecture,dual chains are designed to be responsible for identity authentication and light data storage respectively.The identity chain replaces the identity management function of TA,and the identity information on the chain is encrypted and stored by smart contracts to effectively avoid data leakage,and the data chain replaces the functions of database indexing and permission control to realize on-chain verification,offchain storage,fine-grained access control.The dual-chain architecture with cross-chain mechanism can complete data interoperability between chains.2.Key management mechanism of smart contract.RSU provides stable computing power as an edge node of Io V,introduces Chinese digital signature algorithm and encryption and decryption algorithm SM2,can generate,update and revoke key pairs for vehicles automatically through smart contract,realizes mutual authentication of peer nodes,effectively realizes the mapping of public key and identity based on the anti-tampering feature of blockchain,and the public key of vehicles can be safely stored in the identity chain,further improving the transparency and fairness of key management,reducing management costs,and eliminating the single point of failure in centralized TA scheme.3.Data management mechanism of smart contract.Implementing a secure asynchronous uploading strategy for the characteristics of car mobility and mobile network instability,introducing attribute set permission control to give users greater control over personal data? implementing a keyword matching retrieval scheme in data retrieval by combining the Merkle Prefix Tree（MPT）transaction retrieval algorithm,and filter redundant data by marking transactions? using the content addressing feature of IPFS file system to store the Io V data in distributed nodes,the off-chain storage scheme effectively reduces the storage overhead of blockchain and performance load of Io V devices,and achieves a more secure and efficient storage method.Finally,this thesis designs,implements and tests the Io V information management system based on the dual-chain vehicle chain.Simulation tests conducted on the Ethernet platform show that the dual-chain vehicle chain and smart contracts proposed in this thesis can meet the functional requirements of Io V,with advantages in storage consumption,query efficiency,transaction throughput,communication latency and security.