Research On Lightweight DAG-based Blockchain Storage Approach For Vehicular Social Networks

The emerging of vehicular social networks has brought richer social features to information transmission in road traffic networks,making data sharing more effective.However,the rich semantics of information transmission also brings greater challenges to the security and privacy protection of data in vehicular social networks.Blockchain can provide safe and reliable data storage for vehicular social networks due to its security and tamper-proof characteristics.However,the chain-based blockchain lacks of parallelism,and the lower throughput makes it difficult to meet the requirements of application with rapidly increasing data in vehicular social networks.In addition,the existing blockchain system requires each node to store full ledger data,which is also difficult to directly apply to the resource-constrained vehicular social networks.In order to reduce the storage overhead caused by the redundancy of blockchain data,the lightweight blockchain for the vehicular social networks(LDV)is proposed.LDV uses a Directed Acyclic Graph(DAG)to organize and store transactions,and two data reduction approaches are proposed in LDV,which is parallel and lightweight.Based on the social attributes of the vehicular social networks,LDV introduces a social-based data reduction method to reduce the storage overhead.In details,the nodes only need to store the data in the topic of interest,and alleviate the storage pressure of the node by avoiding the storage of unnecessary data.At the same time,in order to avoid the further increase in storage overhead in a single topic group,based on the timeliness of the data,a historical data pruning method is proposed to reduce storage cost by reducing the amount of data redundancy.For the data query and verification requirements,the path proof and topology preserving mechanism is proposed to ensure the verifiability of query results.In order to evaluate the storage cost of the LDV and verify the effectiveness of the proposed data reduction approaches,the size of blockchain data is measured under different storage methods.The experiment results show that the proposed data storage method can effectively save the storage space.Specifically,LDV can save 97.13% storage space and has good storage scalability.