An Efficient and Robust Committee Structure for Sharding Blockchain

TL;DR

This paper proposes a new committee structure with reputation-based leader selection and recovery mechanisms to enhance the efficiency and robustness of sharding blockchain systems, addressing key scalability and security challenges.

Contribution

It introduces a reputation mechanism, referee committees, and recovery procedures to improve sharding blockchain performance and security, which are novel solutions to existing issues.

Findings

Reputation-based leader selection significantly improves system performance.

The proposed recovery procedure effectively evicts malicious leaders.

Simulations confirm the robustness and efficiency of the new design.

Abstract

Nowadays, sharding is deemed as a promising way to save traditional blockchain protocols from their low scalability. However, such technique also brings several potential risks and huge communication overheads. An improper design may give rise to the inconsistent state among different committees. Further, the communication overheads arising from cross-shard transactions unfortunately reduce the system's performance. In this paper, we first summarize five essential issues that all sharding blockchain designers face. For each issue, we discuss its key challenge and propose our suggested solutions. In order to break the performance bottlenecks, we propose a reputation mechanism for selecting leaders. The term of reputation in our design reflects each node's honest computation resources. In addition, we introduce a referee committee and partial sets in each committee, and design a recovery procedure in case the leader is malicious. Under the design, we prove that malicious leaders will not hurt the system and will be evicted. Furthermore, we conduct a series of simulations to evaluate our design. The results show that selecting leaders by the reputation can dramatically improve the system performance.