DX protocol: a high-performance sketch-based set reconciliation protocol for blockchain propagation

Efficient block propagation is critical to the performance and scalability of blockchain networks. High propagation latency not only slows synchronization but also increases the risk of forks and orphaned blocks. Existing propagation protocols suffer from bandwidth inefficiency, high false-positive rates, or insufficient compression. In this work, we propose the DX protocol, a lightweight and high-performance sketch-based set reconciliation scheme that utilizes a novel data structure called the DX sketch to encode transactions as fingerprint-based structures, supporting subtraction and decoding, enabling fast and accurate set reconciliation. By reducing redundant data transmission, DX improves propagation efficiency in both optimistic (fully synchronized) and pessimistic (partially missing) mempool scenarios. Theoretical analysis shows that the DX sketch achieves lower space complexity and a lower false-positive probability compared to Bloom filters and IBLTs. Extensive experimental results indicate that DX reduces propagation latency by up to 10 times and bandwidth costs by up to 60% compared with state-of-the-art protocols, such as Graphene and Compact Blocks, while maintaining low false-positive rates, demonstrating that DX is a high- performance, practical solution for scalable blockchain propagation, improving upon existing designs without introducing radical changes to protocol flow.