Research And Implementation Of Blockchain Consensus Algorithm

Blockchain is the core supporting technology of the digital cryptocurrency system represented by bitcoin,which is a kind of decentralized distributed ledger.It has attracted intense attention since it changed the problem of the need of a trusted third party in traditional payment method.Blockchain has broad application prospects in the fields of finance,public affairs management,digital copyright,etc.How to formulate a set of rules to unify the nodes is the core of the blockchain and the important responsibility is borne by consensus algorithm.At the same time,consensus algorithm affects the throughput,transaction acknowledgement delay,and fault tolerance of the system.Based on the above background,we propose an consensus algorithm based on credit reward and punishment called VPBFT consensus algorithm.The algorithm is validated experimentally,the main work of this thesis is as follows:(1)We studied the fundamental of classical blockchain consensus algorithm POW,POS and DPOS.Based on this,we compare them and analyze their advantages and disadvantages of them.(2)Based on the problems of low throughput and high delay of transaction confirmation in the classical block chain consensus algorithm,we propose an consensus algorithm based on credit reward and punishment called VPBFT consensus algorithm.This algorithm divides the nodes into two parts: accounting nodes and normal nodes.Only the accounting nodes can participate in the consensus process,so we reduce the number of the nodes who participate in consensus process.At the same time,we divide nodes into different states,update the status of the node according to the credit reward and punishment.So we realize the update of the accounting representative members and the dynamic changes of the nodes.Second,we use a monitoring-based checkpoint protocol combines a mixed group Byzantine fault tolerance consistency protocol to reduce communication overhead.The VPBFT consensus algorithm is designed and implemented based on this.(3)Aiming at analyzing the performance of the VPBFT consensus algorithm,we design the experiment.The experiment is designed from three aspects of throughput,transaction confirmation delay,and fault tolerance.Based on the results,the VPBFT consensus algorithm is compared with the classical blockchain consensus.(4)We apply Radix-Merkle Tree to blockchain instead of Merkle Tree,which changed the drawback of Merkle Tree not being able to verify status information.At the same time,due to the high retrieval efficiency of the Radix tree and Merkle tree,the retrieval efficiency isimproved.Then aiming at improving the security of transaction,we design the account status tree based on Radix-Merkle Tree.Based on the above,we have implanted the function of checking account balance.