Study On Blockchain Scalability And Efficient Smart Contract Processing Based On Two-layer Consensus

As a distributed ledger,blockchain is widely used in finance,technology,government affairs and people’s livelihood due to its characteristics of decentralization,trustlessness,and immutability,and has become one of the current research hotspots.However,because of its distributed feature,blockchain systems have poor scalability.In response to this question,scholars have proposed a number of blockchain scalability schemes based on the sharding scheme,but these works have the following problems:(1)Most blockchain scalability sharding schemes based on Proof of Work(Po W)have higher requirements on node computing power consumptions and lower throughputs;(2)The blockchain system based on sharding technology requires multi-party communication to ensure atomic submission when processing cross-shard smart contracts,resulting in low transaction efficiency.Aiming at the above two problems,this thesis designs a blockchain scalability scheme based on two-layer consensus and a cross-shard smart contract processing scheme that separates execution and verification.The main work are as follows:(1)In this thesis,a two-layer consensus algorithm is designed by combining the Delegated Proof of Stake(DPo S)and the improved Practical Byzantine Fault Tolerance(PBFT).The schem applys Verifiable Random Functions(VRF)to ensure the security of the blockchain sharding process,and utilizes BLS aggregate signatures to optimize the communication process of the PBFT algorithm to improve consensus efficiency.In addition,this thesis proposes a commitment-confirmed cross-shard transaction processing protocol,which guarantees the atomic processing of transactions in the entire system.Compared with other schemes,the throughput of this scheme is improved by about 20%.(2)Based on the two-layer consensus algorithm,this thesis proposes a cross-shard smart contract processing scheme that separates execution and verification.This scheme separates the execution of smart contracts from the verification process by setting up an executive committee,which resolves the problem of chronic executing smart contract codes and improves the efficiency of cross-shard smart contract transactions.Next,this thesis analyzes the security advantages of this scheme in three aspects: error recovery,robustness and liveness.The evolutions show the scheme in this thesis significantly improves the efficiency of cross-shard smart contract transactions and reduces the transaction delay,and the transaction volume per unit time is about 30% higher than other schemes.