Research On Optimization Of Practical Byzantine Fault Tolerant Algorithm For Blockchain

As the core technology of the blockchain,consensus algorithm can maintain the consistency of data among different nodes in the decentralized environment.At present,the most widely used consensus algorithm in permissioned blockchain is Practical Byzantine Fault Tolerance Algorithm(PBFT).As a traditional distributed consensus protocol,PBFT needs to be designed and optimized in performance and reliability when it is applied to the blockchain.To solve the problem of low performance of PBFT in permissioned blockchain,this paper conducts the performance optimization of PBFT based on multi signature.Firstly,we design a hierarchical scheme.The nodes of the blockchain are divided into consensus nodes,candidate nodes,and ordinary nodes.We realize parallel transaction logic verification in the primary and backups by delegating candidate nodes to verify the validity of transactions preliminarily.Secondly,in order to reduce the pressure on primary node's exit bandwidth in multicasting block,we design a block packing mechanism based on transaction hash.This greatly reduces the processing time of the primary node in block serialization and the exit bandwidth pressure in multicasting block.Experimental results show that this optimization significantly improves the transaction throughput of blockchain and reduces the transaction delay.To solve the problems that PBFT can't detect the status of nodes in the consensus node cluster,the primary node is selected in turn and easy to be attacked,and the consensus node cluster is fixed and can't join and exit nodes dynamically,this paper conducts the reliability optimization of PBFT based on trust mechanism.Firstly,by introducing a detection factor,the performance of the consensus nodes in the cluster is detected,and combining with the adaptive primary node election mechanism,the honest nodes are rewarded with a higher probability of becoming the primary,which can improve the stability of the algorithm.Secondly,in order to eliminate Byzantine consensus nodes,this paper designs a dynamic promotion-demotion protocol,which uses trusted candidate nodes to replace Byzantine nodes in the consensus node cluster,which greatly improves the reliability of the system on the premise of ensuring the security and liveness of the algorithm.