Accountable Secret Committee Election and Anonymous Sharding Blockchain Consensus

Consensus protocols play a crucial role in determining the security and performance of blockchain systems, with committee-based consensus protocols being particularly important, especially in sharding consensus protocols. Anonymous election of committee nodes can mitigate DDoS attacks and bribery attempts. This approach can also be applied to sharding systems to mitigate the risk associated with a single vulnerable shard. However, current node secret selection schemes still present remaining issues. Single secret leader election schemes struggle to elect multiple leaders with equal anonymity, and existing secret committee election schemes lack adequate measures for tracking malicious nodes. To address these issues, we propose accountable secret committee election schemes that not only regulate the number of nodes but also maintain anonymity during the phases of leader proposal and verifier voting. Furthermore, our schemes enable the tracing of malicious nodes in a threshold way. In addition, we introduce two efficient threshold traceable membership proof schemes for both ad hoc and interactive scenarios. Unlike traceable ring signatures, our scheme can trace malicious nodes even after a single malicious behavior. Subsequently, we apply the accountable secret committee election scheme to sharding blockchains and devise a fully accountable anonymous consensus protocol. The experiment demonstrates that this protocol can elevate the difficulty of corrupting a single shard to the level of compromising the entire system, thereby significantly enhancing the security of the sharding system.