Research And Improvement Of Blockchain Consensus Algorithm Based On Delegated Proof Of Stake

The blockchain appears in people's field of vision with the birth of Bitcoin.With the digital currency represented by Bitcoin is popular all over the world,blockchain has been studied and paid attention by major organizations and economies around the world as the underlying technology of Bitcoin.Blockchain technology has a wide range of applications in the fields of finance,logistics,credit reporting and intellectual property because of its de-centralization,unchangeable,unforgeable and openness.As the core technology of blockchain technology,consensus algorithm directly affects the performance of blockchain system.Since the emergence of blockchain technology in 2008,the mainstream consensus algorithms used in public blockchains are PoW,PoS,and DPoS.These traditional consensus algorithms are no longer able to meet requirements in one or a few aspects in terms of performance indicators such as resource consumption,the time of generating a blcok and distribution of accounting rights.This paper introduces the idea of PoW's computing power competition into DPoS,and designs a consensus algorithm with downgrade mechanism after in-depth analysis of the working principle of the consensus algorithm mentioned above,which is named Delegated Proof of Stake with downgrade(dDPoS).The main idea of the dDPoS algorithm are as follows:(1)The dDPoS algorithm divides the consensus process into two steps,and separates the individual's rights from the power that generates the block.In the first step,the idea of PoW's computing competition is used to “screen” a certain number of consensus nodes in the nodes of the whole blockchain network;then,the dDPoS algorithm uses the idea of the DPoS's authorization mechanism to vote on consensus nodes,and the witness node set and the alternative node set are elected from the consensus node according to the number of votes obtained.In the second step,the witness node processes the transactions in the system and forms the block,which is broadcast to all consensus nodes for verification.If more than 50% of the consensus nodes agree with the block,all nodes in the blockchain system add it to the blockchain;Otherwise,the witness node is determined to be a malicious node,and the dDPoS algorithm start the “downgrade” mechanism of the witness node and the alternative node.(2)The downgrade mechanism is to introduce the downgrade mechanism similar to the modern sports league to quickly replace the malicious nodes: When the witness node is determined to be a malicious node,the witness node falls out of the witness node set and is marked as a malicious node,and the rank number of all witness nodes after the malicious node is decremented by one.The node with ranking number 1 in the alternative node set is upgraded to the witness node set and ranked at the end.The rank number of all alternative nodes after the node with ranking number 2 is decremented by one.Finally,the malicious node falls into the alternative node set and ranks at the end.Finally,this paper use the Java language to simulate the blockchain node and operationsd of the blockchain system based on the fDPoS mechanism,test its performance and analyze the experimental results.The experimental results show that the efficiency of generating blocks with the dDPoS consensus algorithm is approximately one block every 9 seconds,which is much higher than the PoW and PoS consensus algorithms;And the performance of the dDPoS consensus algorithm is better than the DPoS consensus algorithm in the equity allocation of generating blocks;The downgrade mechanism introduced in this paper can also accurately detect and replace malicious nodes,which ensures the normal operation of the blockchain system.