Abstract: At present, the industry seeks to use blockchain to enhance the reliability, trust and security of vehicular internet of things (VIoT) applications. However, the performance limitations pose challenges for blockchain in adapting to the mobility and real-time requirements of VIoT. To solve the above problems, this paper proposes a tree-blockchain consensus (TBC) mechanism based on virtual sharding and directed acyclic graph (DAG), which uses fixed trusted nodes to reach consensus to reduce dependence on mobile vehicle nodes. A tree-blockchain is built based on DAG to achieve parallel validation and uplink of blocks. For the tree-blockchain, a virtual sharding validation mechanism based on matching code is proposed. The validating nodes and transactions are logically grouped and paired through VRF functions and simple hash operations, ensuring the randomness of transaction sharding, reducing the computational overhead of the validation process, and improving consensus efficiency. Security analysis demonstrates that TBC can effectively deal with the common malicious information attacks, Sybil attacks and man-in-the-middle attacks in the network. Simulation results further show that TBC outperforms traditional consensus algorithms, meeting the specific application requirements of VIoT.

Key words: blockchain, vehicular internet of things (VIoT), virtual shading, directed acyclic graph (DAG), matching code