RepShardChain: A Reputation-Based Sharding Blockchain System in Smart City

With the rapid development of smart cities with emerging technologies as the core, the attendant problems of data sharing and data security have attracted extensive attention. As an emerging distributed storage technology, blockchain has the characteristics of decentralization, transparency and credibility, tamper proof, and traceability, which is very suitable for data sharing and storage in smart cities. However, the scalability and consensus mechanisms of blockchain are not applicable to real-time data sharing requirements and resource-constrained Internet of things (IoT) devices in smart cities. According to the needs of smart cities, this paper designs a data sharing model RepShardChain based on reputation and sharding blockchain, designs a reputation-based proof-of-work (PoW) consensus mechanism to adapt to the IoT devices with limited resources, designs a reputation-based random sharding scheme to avoid malicious attacks, designs an incentive mechanism that takes into account the rewards and punishments of nodes, and incentivizes nodes to perform normal behavior to obtain more rewards, so as to realize the safety and efficiency of the blockchain. And we analyze the security of the proposed RepShardChain against various attacks. Simulation experiments show that the proposed model has higher throughput and higher security than the traditional blockchain.