Improving the Performance of Blockchain Sharding Protocols with Collaborative Transaction Verification

Sharding is a promising approach to scalable blockchains. While sharding eliminates duplicate work between shards, it does not remove intra-shard duplication, i.e., every peer has to verify all transactions in its shard, thus becoming a newly exposed bottleneck. Aiming to improve the performance of individual shards, we propose Collaborative Transaction Verification (CTV), which allows peers to verify fewer transactions by sharing verification results. Equipped with dependency awareness, CTV guarantees that peers reach the same system state despite different transaction verification and execution orders. We implemented an OmniLedger-like sharding protocol based on Bitcoin Core and integrated CTV into the protocol. The evaluation results show that CTV can improve the performance of a shard by 2.6x.