Multi-round Consensus Scheme that Utilizes Statemerge to Reduce the Rollback Probability under State Sharding

Sharding is one of the core technologies to solve the scaling problem of today's blockchain systems, among which state sharding is most likely to essentially solve the scalability problem of public blockchian. However, after sharding, the number of nodes is much lower than that before sharding, which reduces the cost of attack and makes it easy to reach a high proportion of Byzantine nodes in a shard, thus failing to reach a consensus. Secondly, each node under state sharding only keeps the state information of its own shard, so other shards cannot work directly instead of the attacked shard. Therefore, a multi-round consensus scheme that utilizes state-merge to reduce the rollback probability under state sharding is proposed. First, this paper proposes a state-merge model for the case of transaction rollback in the attacked shards under state sharding, which allows highperformance nodes in the base shards to synchronize the state information of their brothers, and then revert it to the upper virtual shard, thus enabling the completion of consensus verification of the transactions in the base shard. After that, a state synchronization method based on alternate nodes is proposed, and the nodes that have completed the synchronization enter the sequence of alternate nodes, which in turn can complete the state merging and the subsequent multiple rounds of consensus. Experiments show that for the case of transaction rollback in the attacked shards under state sharding, this scheme can restore the consensus efficiency of nodes, which ensures the performance of the blockchain system, and at the same time safeguards the security of the blockchain network.