A Study On Blockchain Consensus Algorithm Based On Tree Topology

In the study of blockchain technology,consensus algorithm is one of the most important parts.Blockchain consensus algorithms such as Proof of Work(PoW)have high degree of decentralization,but they have low throughput,weak consistency and high delay.Other than PoX consensus algorithms,Practical Byzantine Fault Tolerance(PBFT)also plays an important role in the consensus algorithms.PBFT does not have the issue of forks,but in a system that has nodes,its communication complexity is as high as O(N~2),and it is only applicable to a system in which the number of nodes is below 100.HotTree is designed by improving the star-network in HotStuff,arranging nodes in a virtual tree and parallelizing the process of signature aggregation between honest nodes in tree topology.HotTree implements a new blockchain structure based on two chains.First of all,a committee is elected using PoW to generate transaction block that contains transactions.In the committee,improved HotStuff consensus algorithm is used to generate the transaction blocks.For all nodes that agree with each other,the roots of their subtrees send their aggregated signatures to the leader of current round.By using this virtual tree,leaders only need to process less messages,this method relieves the performance pressure off leaders.In addition,HotTree uses Verifiable Random Function(VRF)to elect a new leader in a committee,comparing to electing a leader in sequence,it is more resistant to attacks.Last but not least,HotTree improves the original incentive mechanism of equal distribution that Byz Coin uses,so that nodes are rewarded in a positive correlation with proportion of consensus participation.In conclusion,our tests show that HotTree is a consensus protocol with high throughput,low delay,high anti-attack ability,strict consistency and more fairness.