区块链共识机制研究综述

Overview on Blockchain Consensus Mechanisms

自比特币被提出以来,数字货币开启了新的时代,而其背后的区块链技术也逐渐受到各界人士的重视.共识机制作为区块链技术的核心,决定了区块链的安全性、可扩展性和去中心化程度等许多重要特性.本文从系统模型、共识机制本质、激励设置和安全攻击等角度对现有共识机制进行研究.首先研究了共识机制的模型,对网络模型、敌手模型和腐化模型给出定义和分类.在不同的模型基础上,将现有共识机制分为经典分布式共识和区块链共识.其次,对于经典分布式共识,研究了PBFT、Paxos等分布式一致性算法及其改进,给出了算法具体流程和优缺点分析.再次,对于区块链共识,根据应用场景的不同将其分为授权共识机制和非授权共识机制,将非授权共识分为基于工作量证明的共识机制、基于权益证明的共识机制、采用单一委员会的混合共识、采用多委员会的混合共识和其他共识机制.对于每一类共识机制,给出其基本流程,深入分析典型方案,指出其存在的优缺点、交易规模以及可能面临的攻击方式.最后,指出了区块链时代共识机制在安全、扩容、启动、激励等层面的研究热点和发展方向.

Since the introduction of Bitcoin,digital currency has entered into a new era,and the underlying Blockchain technology has gradually attracted the attention of researchers.As the core of Blockchain technology,the consensus mechanism determines the security,scalability,and decentralization of Blockchain.This paper studies the existing consensus mechanisms from the perspectives of system model,consensus mechanism,incentive setting,and security attack.Firstly,network models, adversary models,and corruption models of consensus mechanisms are defined and classified.Based on different models,existing consensus mechanisms are divided into classic consensus and Blockchain consensus. Secondly,for the classical consensus,PBFT,Paxos,and the latest improvements are briefly introduced.In addition,a concrete algorithm,advantages,and disadvantages are given.Thirdly, Blockchain consensus is divided into permissioned consensus and permissionless consensus according to different application scenarios.This paper further divides the permissionless consensus into proofof- work based consensus,proof-of-stake based consensus,single-committee based hybrid consensus, multiple-committee based consensus,and other consensus.For each type of consensus mechanism, the basic procedure is given,and typical solutions are analyzed in depth.The advantages and disadvantages, transaction throughput,and the possible attack methods of the consensus mechanism are given.Finally,this paper points out some research hotspots and development directions of Blockchain consensus mechanisms in terms of security,capacity expansion,startup,and incentive.