LDV: A Lightweight DAG-Based Blockchain for Vehicular Social Networks

As social networks are integrated into the Vehicular Ad Hoc Networks (VANETs), the emerging Vehicular Social Networks (VSNs) have gained massive interests. However, the security and privacy of data generated by various applications in VSNs is a great challenge, which blocks the further development of VSNs. The emerging blockchain technology seems to be a good catalyst for the development of VSN with its high security and irreversible features, which can be also a data management tool for rapidly generated data of VSNs with tamper proof. However, the full duplicates of blockchain data need to be stored in each node to ensure security, which is unacceptable for vehicles with limited resource. In this paper, to address the above storage challenge, a lightweight Directed Acyclic Graph (DAG) based blockchain (LDV) is proposed for resource-constrained VSNs. Specifically, based on the in-depth analysis of VSNs, we propose the social-based data reduction approach. In detail, each node only stores the interested data within the topic groups of interest and ignores the irrelevant data. To avoid the huge storage cost within large-scale groups with large amounts of data, we further present the historical data pruning method within a group, which meets the storage requirement by reducing the number of duplicates stored in each node. Experimental results show that LDV can save 97.13% storage space and has good scalability.