SP-Chain: Boosting Intrashard and Cross-Shard Security and Performance in Blockchain Sharding

A promising way to overcome the scalability limitations of the current blockchain is to use sharding, which is to split the transaction processing among multiple, smaller groups of nodes. A well-performing blockchain sharding system requires both high performance and high security in both intra- and cross-shard perspectives. However, existing protocols either have issues in protecting security or tradeoff great performance for security. In this article, we propose SP-Chain, a blockchain sharding system with enhanced security and performance for both intra- and cross-shard perspectives. For the intrashard aspect, we design a pipelined two-phase concurrent voting scheme to provide high system throughput and low transaction confirmation latency. Moreover, we propose an efficient unbiased leader rotation scheme to ensure high performance under malicious behavior. For the cross-shard aspect, a proof-assisted efficient cross-shard transaction processing mechanism is proposed to guard cross-shard transactions with low overhead. We implement SP-Chain based on Harmony, and evaluate its performance via large-scale deployment. Extensive evaluations suggest that SP-Chain can process more than 10000 tx/s under malicious behaviors with a confirmation latency of 7.6 s in a network of 4000 nodes.