Abstract:

To solve the problems of unreasonable primary node selection and high transaction delay in Practical Byzantine Fault Tolerance （PBFT） consensus mechanism， an improved PBFT consensus mechanism based on Verifiable Delay Function （VDF） was proposed， called VPBFT. Firstly， a voting mechanism was introduced into original PBFT algorithm to select nodes， which were divided into ordinary nodes， voting nodes， backup nodes and consensus nodes according to random voting results. Secondly， the primary node selection mechanism of PBFT algorithm was improved by using VDF for primary node selection， and random numbers were generated by the hash value of the previous block and the user’s private key to increase the unpredictability of the primary node and ensure the consensus security. Finally， the consensus process of PBFT algorithm was optimized by simplifying consensus process into three stages， thereby reducing the algorithm complexity and communication overhead. Experimental results show that the proposed VPBFT outperforms the original PBFT algorithm in terms of security and consensus performance.

Key words: blockchain, Practical Byzantine Fault Tolerance (PBFT), Verifiable Delay Function (VDF), voting mechanism, hash function, transaction delay

摘要：

针对实用拜占庭容错（PBFT）共识机制的主节点选择不合理和高交易延迟问题，提出一种基于可验证延迟函数（VDF）的改进实用拜占庭容错共识机制VPBFT。首先，针对原有的PBFT算法引入投票机制进行节点选取，并根据随机投票结果将节点划分为普通节点、投票节点、备份节点和共识节点；其次，改进PBFT算法主节点选举机制，即使用VDF进行主节点选举，并利用上一区块哈希值和用户私钥生成随机数，增加主节点的不可预测性，保证共识安全；最后，优化PBFT算法的共识过程，将共识过程简化为三个阶段，从而降低算法复杂度，减少通信开销。实验结果表明，所提出的VPBFT在安全性和共识性能方面优于原有PBFT算法。

关键词: 区块链, 实用拜占庭容错, 可验证延迟函数, 投票机制, 哈希函数, 交易延迟