Analysis And Improvement Of Blockchain Multi-Type Consensus Mechanism

With the rapid development of blockchain technology,the research of consensus mechanism is becoming more and more important.At present,there are a wide variety of consensus mechanisms,including Proof-of-Work(Po W),Proof-of-Stake(Po S),Delegated-Proof-of-Stake(DPo S)and Practical Byzantine Fault Tolerance(PBFT).However,these mainstream consensus mechanisms have their own shortcomings.This thesis analyzes and improves the three consensus mechanisms: Po W,DPo S and PBFT.The main contents are as follows:1.Aiming at the problem that the randomness analysis of existing Po W mechanisms is not precise enough,the concept and analysis model of Po W mining randomness are proposed.For the hash function,the mining randomness of each bit will be different.The formula of mining randomness is given.The mining randomness formula of continuous bit string is given.Two evaluation models for mining randomness are proposed.The experiments for SHA-256,SM3 and SHA-3 are conducted to analyze their mining randomness.For each hash function the best mining position under the fixed difficulty and the best mining difficulty under the fixed mining position are obtained.2.To address the issue of inaccurate DPo S voting processes,the DPo S voting model based on Vague Set is improved.For the influence factor of abstention votes,the conversion formula from Vague Set to Fuzzy Set is improved,so that the influence factor of abstention votes increases with the increase of the number of valid votes.At the same time,the weight of each node is added on the original basis,which conforms to the actual situation of DPo S.The improved formula can prove that the Fuzzy Set values increase with the increase of affirmative votes and decrease with the increase of negative votes.Compared with the original scheme and the improved scheme,the experiments show that the improved scheme makes the distribution of Fuzzy Set values more dispersed and reduces the same situation of Fuzzy Set values,which make the voting process more fair.3.To address the vulnerability of PBFT master nodes to attacks,a PBFT mechanism based on proxy and anonymity is proposed.In the Pre-Prepare and Prepare phase of PBFT,a linkable ring signature is used to replace the original signature,that other nodes cannot know the identity of the master node.It reduces the probability of the master node being attacked.At the same time,the association label of the linkable ring signature is used to determine whether the message was sent by the same node.In addition,each node has its own proxy node.When the node cannot participate in the consensus in time,the proxy node can participate in the consensus to avoid the node being mistaken for a malicious node,thereby improving the security and stability of PBFT.