基于贡献值和难度值的高可靠性区块链共识机制  

A Highly Reliable Consensus Mechanism for Blockchain Based on Contribution and Difficulty Values

作　　者：何泾沙 张琨 薛瑞昕 朱娜斐 贺鹏[2] 宋洪宇 杜伟东 甘宇 HE Jing-Sha;ZHANG Kun;XUE Rui-Xin;ZHU Na-Fei;HE Peng;SONG Hong-Yu;DU Wei-Dong;GAN Yu(Faculty of Information Technology,Beijing University of Technology,Beijing 100124;College of Computer and Information Technology,China Three Gorges University,Yichang,Hubei 443002)

机构地区：[1]北京工业大学信息学部,北京100124 [2]三峡大学计算机与信息学院,湖北宜昌443002

出　　处：《计算机学报》2021年第1期162-176,共15页Chinese Journal of Computers

基　　金：国家重点研发计划课题(2019QY(Y)0601)资助.

摘　　要：基于贡献值证明(PoC)的区块链共识机制是面向知识产权保护与交易应用场景提出的一种区块链共识机制,通过计算节点用户的贡献值,由贡献值最大的节点获得新区块的记账权.然而,由于PoC会造成记账节点具有很强的确定性,一旦该节点未能正常完成记账出块,网络中其它节点将始终保持在挂起等待状态,系统将陷于停滞状态,无法继续运行.为了使PoC区块链共识机制能够适用于公有链应用场景,本文提出基于贡献值和难度值(PoC+PoW)的区块链共识机制,使选择新区块记账权的节点具备一定的不确定性,能够有效解决PoC共识机制中存在的系统运行挂起缺陷.在PoC+PoW共识机制中,节点在工作量证明(PoW)竞争中所对应数学难题的难度值根据节点的贡献值(PoC)进行动态确定,是一种对单纯基于PoC共识机制的灾备方案,以确保系统运行的可靠性.本文提出的PoC+PoW方案根据节点的贡献值排名为节点分配相应的PoW难度值,节点再通过PoW共识机制竞争记账权.引入PoW后的共识机制最大程度地尊重PoC贡献值排名,使节点的记账出块率与其贡献值成高度正比,在系统运行层面则保证记账出块率达到或无限趋近100%,有效解决PoC带来的系统运行挂起问题.本文从节点贡献值排名、相邻贡献值节点间值差以及分组方式三个角度设计PoW难度值分配算法,并通过实验验证难度值分配算法的合理性和有效性.同时,通过实验与传统PoC共识机制在记账出块时延方面进行对比分析,进一步验证了PoC+PoW方案的优越性和可行性.A consensus mechanism for blockchain based on proof of contribution(PoC)is a kind of consensus mechanism that is suitable for the application scenarios of intellectual property protection and transaction.In the PoC mechanism,the contribution values of user nodes are calculated periodically and the node with the largest contribution value will assume the right for the construction of a new block.However,the PoC consensus mechanism has the problem that the node that constructs the new block in the current round exhibits the property of strong certainty.If the node that is supposed to construct the new block in the current round fails to do so,all the other nodes will remain in the waiting state and the system will hang and execution can no longer continue.To make the PoC blockchain consensus mechanism applicable to the public chain scenario,this paper proposes a new consensus mechanism based on the contribution value as well as on the difficulty value in the proof of work consensus mechanism(PoC+PoW).In the PoC+PoW consensus mechanism,some uncertainty is added into the process of determining the right for the construction of a new block to overcome the shortcomings of the original PoC consensus mechanism.In PoC+PoW,the difficulty values of the mathematical problem that participating nodes try to solve in the PoW competition is dynamically determined according to the PoC values of the nodes.The proposed mechanism can thus be viewed as a disaster recovery scheme for the PoC consensus mechanism to ensure the reliability of the system operation.The proposed PoC+PoW consensus mechanism would allocate a corresponding PoW difficulty value to a node according to the ranking of the contribution value of the node.All nodes then compete for the right for bookkeeping and block construction through the PoW consensus mechanism.The new consensus mechanism that incorporates PoW would still fully respect the ranking of the contribution values from PoC to ensure that the probability of constructing a new block by a node is highly pr

关 键 词：区块链 共识机制 贡献值 贡献值证明 难度值 工作量证明 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论]