Research On Optimization Scheme Of Blockchain Performance Based On Chain Extension

In 2008,Nakamoto published the Bitcoin white paper,and the birth of Bitcoin triggered a wave of researchers engaged in blockchain technology research.As a new application mode of computer technology including distributed data storage,point-to-point network,consensus mechanism and encryption algorithm,Blockchain is characterised by decentralization,non-tampering and traceability,and is attracting more and more attention in the fields of finance,digital copyright,notarization and traceability of goods with broad application prospects.The current implementation of blockchain systems generally suffer from performance and capacity deficiencies,making it hard to achieve deeper popularity and application.In order to solve these problems,researchers have proposed a variety of solutions including Block Capacity Increment,Witness Isolation,Lightning Network,DAG,Sharding,etc.These solutions are divided into offline-based(Off-chain)solutions and online-based(On-chain)solutions according to the difference in design levels.The Off-chain solution allows small and frequent transactions to occur on side chain which in parallel with the main chain and endorsed by the main chain.The On-chain has higher research values by directly modifying the blockchain basic framework to support high performance.The Sharding mechanism improves the overall transaction performance of the system by dividing the transactions into multiple shards for parallel processing,it is considered as the most probable solution to the blockchain bottleneck.Blockchain projects using the Sharding mechanism include Ethereum 2.0,Zilliqa and QuarkChain.However,the research on Blockchain Sharding is still in starting stage and it's very complex to achieve a Sharding system,the current implement schemes needs to solvecertain problems,including the of rationality of network sharding,the security of transactions in one shard and the difficulty of processing cross-shard transactions.The main work and results of this paper are as follows:1.Introduce the key technologies of the blockchain and the shortcomings of the current blockchain system;2.Summarize the current mainstream blockchain performance improvement scheme based on chain expansion;3.Aiming at the problem of low efficiency and unreasonable sharding,we proposed the “Jump Hash based Dynamic Weight Sharding Algorithm(JHDWS)”.The shards' info is mapped to the two-dimensional matrix,and the nodes are divided into corresponding target shard only need to calculate the row and column information of the matrix.The time complexity of sharding construction is reduced to nO)(log from nO)(.The adjustment of the shard is converted into a dynamic transformation of the matrix,which reduces the maintenance cost.4.For the problem of the weak security of transactions and the complexity of cross-shard transactions in common sharding system,the “Multi-primary-node asynchronous consensus group algorithm(MACG)” is proposed,we picked nodes with good performs to form an asynchronous consensus group to verify and deal transactions,which improves the security and transaction performance greatly.5.Through theoretical analysis and experiments,the blockchain system based on JHDWS sharding algorithm and MACG consensus can achieve a transaction performance of 5000 tps,the system can also effectively resist "1%" Sharding Attack and Sybil Attack,satisfying the demand of most application systems.Blockchain system is very complex and requires comprehensive consideration of factors such as security,decentralization and scalability.With the rapid development of technology,the blockchain will be promoted to a faster application.