Design Of E-voting Bulletin Board System Based On Synchronous Distributed Algorithm

E-voting systems are a powerful technology for improving democracy by reducing election cost,increasing voter participation,and even allowing voters to directly verify the entire election procedure.Furthermore,the e-voting Bulletin Board(BB)system,known as "a broadcast channel with memory",is a key component in e-voting systems.During the election,the BB system publicizes valid ballots and related proofs,which allows clients to conduct the validation checks during the voting process.At present,the research on the e-voting BB system requires the server to ensure security.Existing practical e-voting BB systems can only tolerate f<[n/3]faults under the asyn-chronous assumption,which makes the system unable to resist malicious attacks in a more complex network environment.In this thesis,based on the research of synchronous Byzan-tine consensus algorithm,an e-voting BB system based on an improved efficient synchronous Byzantine consensus(ESBC)protocol is designed and implemented.The system achieves Byzantine fault tolerance off<[n/2]under the assumption of synchronization and pro-vides assurance of integrity,verifiability,and non-reusability of the e-voting system.The main work of this paper is as follows:1.This thesis begins with the research on distributed consensus problems.The ESBC proto-col is investigated under synchronized assumption,which is a Byzantine fault tolerant(BFT)distributed consensus algorithm.With the understanding of its mechanism,the ESBC pro-tocol is implemented and its performance is tested,which provides critical parameters for subsequent discussions and experiments.2.The ESBC algorithm is improved under the synchronization assumption,and a consensus algorithm based on time slice sequence is proposed.The server node caches the sequence request to the client and submits the consensus request at a fixed period.The synchroniza-tion for balloting in each time slice is modeled as a consensus problem in the Byzantine agreement.Multiple time slice sequences are serially resolved,and the consensus within a single time slice is resolved by parallel ESBC Byzantine broadcast.The improved algorithm guarantees the safety and liveness without increasing the complexity of the protocol,and maximizes the efficiency of the protocol.3.Based on the improved ESBC algorithm,a new scheme of an e-voting BB system is designed.The system works under the assumption of synchronization,and the public key system is applied to ensure the integrity and verifiability of the voting process.Finally,the simulation of the e-voting BB system proposed in this thesis is carried out.The system is deployed on the Alibaba Cloud cluster to test the influence of the number of geo-replicated server nodes on the throughput and latency of the system.The simulation results show that the system can realize the basic voting,query and verification of the e-voting sys-tems;it can tolerate f<[n/2]Byzantine faults under the synchronization assumption,with good throughput and second-level response time.