An Improved Scheme Of Low Cost Practical Byzantine Fault Tolerant Consensus Algorithm

Since the publication of Bitcoin White Paper,Blockchain has been explored by scholars and researchers as an emerging computer technology.Blockchain has been developing for more than a decade.Due to the decentralized,trustless,tamper-resistant nature of blockchain technology,the technology is also gradually applied to finance,supply chain,logistics,insurance,cross-border payment and other fields.Consensus mechanism,as the top priority of blockchain technology,is used to achieve data consistency in the distributed system,while consistency is the most important issue in the distributed system.In addition,consensus mechanism also determines the efficiency of the blockchain system to a large extent.In the work of this paper,the mainstream consensus mechanism in the blockchain is first described and summarized,focusing on the analysis of the PBFT consensus mechanism,found that the PBFT consensus mechanism still has the following key problems.Firstly,the scale of network communication complexity reached ~2in the PBFT algorithm,it is difficult to support large-scale network.With the increase of node size,the efficiency will drop sharply and the communication cost is high.Secondly,nodes cannot dynamically join and exit the consensus network,resulting in poor scalability and high cost of adding and deleting nodes.Finally,for malicious nodes in consensus network,there is no protocol to eliminate malicious nodes.Aiming at some existing problems of PBFT algorithm,the main research work in this paper is as follows:(1)In order to solve the problem that the network communication complexity of PBFT algorithm reaches ~2and it is difficult to support large-scale network,an Aggregating-Signature Byzantine Fault Tolerance algorithm is proposed based on aggregating signature.By combining the BLS aggregating signature,to reduce the communication complexity from to().And through the experimental analysis,we can know that the aggregating signature and verification of the aggregating signature are short in time and will not affect the efficiency of the consensus.And the size of the aggregating signature is the same as that of a single signature,which will not bring the burden to the communication and greatly reduce the cost of the application of the Practical Byzantine Fault Tolerant consensus algorithm in the consortium chain.(2)In order to solve the problem that PBFT algorithm nodes cannot join and exit the consensus network dynamically,the concept of coordination node is proposed in this paper.The coordination node is responsible for managing the information of each node in the whole consensus network and coordinating each node to join and exit the consensus network.All node information table and consensus node information table are added for each node to realize the perception of the state of each node in the whole network,and the scheme of dynamically adding and deleting nodes is added to realize the dynamic management of nodes without restarting the network.(3)As there is no protocol designed for eliminating malicious nodes in PBFT algorithm,this paper introduces the node credit value to evaluate the honesty degree of nodes and distinguish honest nodes from malicious nodes.In addition,a protocol is set to kick nodes with low credit value out of the consensus network to prevent nodes with low credit value from harming the security of the whole consensus network.Finally,based on the low-cost Practical Byzantine Fault Tolerant consensus algorithm improvement scheme ABFT algorithm proposed in this paper,the experimental results show that the performance of ABFT algorithm is better than other consensus algorithms in the case of multiple nodes.It effectively reduces the delay of consensus and improves transaction throughput,and reduces the cost of communication.In addition,it supports the nodes to join and quit the consensus network quickly and dynamically,so that the consortium chain can accommodate a large number of nodes.