Optimization Of Blockchain Consensus Mechanism Based On DpoS Algorithm

As a virtual currency,bitcoin has attracted people's attention ever since it was proposed.As a core technology of bitcoin,blockchain has been applied not only in digital currency,but also in credit investigation,medical treatment,electronic evidence and other fields by virtue of data transparency,tamper-proof and decentralization.At present,the Public Blockchain has many characteristics,such as the large number of nodes,high degree of freedom,and large data transaction volume,so the efficiency,security and fairness of the blockchain are required to be higher.As a solution to achieve data consistency in blockchain network,consensus mechanism directly determines the performance bottleneck of blockchain,it is the core content of blockchain and one of the important research hotspots.Based on this background,on the basis of Delegated Proof of Stake(DPoS)algorithm,the thesis proposes a Quick Delegated Proof of Stake based on Nodes' Behavior and Borda Count(QDPoSB).The main work of this thesis includes:Firstly,to solve the problem of unbalanced power distribution in DPoS algorithm,this thesis introduces the concept of generation behavior and Borda Count,and proposes a witness election model based on node generation behavior.This model optimizes the election mechanism of the node that generates blocks by monitoring the block production behavior of the witness node,taking the node's malicious behavior and voter's preference as the reference standard,selecting more secure and fair nodes to generate blocks.Then,in order to solve the problems of delayed processing of malicious nodes and too long block validation time in DPoS algorithm,a multi-stage witness node conversion mechanism is designed,which enables the dynamic conversion between the set of election witnesses and the set of candidate witnesses.In addition,the main idea of PBFT algorithm is introduced for block verification to realize timely validation of blocks and broadcast to the blockchain network,so as to quickly process malicious nodes and reduce the confirmation delay of transactions.Finally,the blockchain simulation test is carried out in the experimental environment,and it is compared with the DPoS algorithm from the dimensions of block generation throughput,block validation delay,power of generating blocks and benefit distribution,and treatment measures of malicious node,so as to verify the effectiveness and practicability of QDPoSB algorithm.The work of thesis shows that the QDPoSB algorithm not only retains the advantages of high throughput,lower broadband requirements and strong scalability of DPoS algorithm,but also has better security,fairness and lower block validation delay,and has better applicability.