Research On Blockchain Consensus And Storage Mechanisms

The rise of digital economy accelerates data exchange and transaction verification across industries and sectors.As the core technology of decentralized distributed ledger,blockchain is widely used in the field of digital finance.However,blockchain has problems in the field of digital finance in terms of architecture,information security,and big data on chain,causing challenges of blockchain technology in performance and scalability,security technology innovation,and storage growth.To build an efficient and secure blockchain digital economy system,achieve high consensus scalability,strong consensus security,efficient consensus message propagation and space-saving storage,this dissertation solves the key problems in the blockchain consensus and storage mechanisms,including low scalability of computing and storage,consensus security attacks,low efficiency and relying on controllable nodes mobility during message propagation,privacy leakage during simplify payment verification and large blockchain storage overhead.The main research contributions are as follows:1 Strong transaction processing and node storage capabilities-supported consensus scalability solution:There are scalability limitations in blockchain consensus of largescale digital financial applications,causing that nodes cannot provide the computing,storage and bandwidth capabilities required for transaction processing as the blockchain size grows.Existing typical consensus scalability solutions based on sharding technology realize the scalability of communication and computing,but cannot achieve the storage scalability.To this end,this dissertation researches on the computing and storage scalability problems,designs community assignment rule based on Proof-of-Work(PoW),constructs a Practical Byzantine Fault Tolerance(PBFT)parallel transactions processing mechanism based on sharding technology,and designs the mechanisms of block header storing the state change and node storing block header chain,thereby,improving the scalability of computing and storage.Experiments show that,compared to PBFT and Bitcoin blockchain,the consensus latency is reduced by orders of community numbers and the storage scales twice.2 Nothing at stake and long range attacks-resistant Proof-of-Stake consensus security scheme:Blockchain consensus is executed among trustless distributed nodes,and there are malicious node attacks that destroy consensus security.The existing typical Proof-of-Stake(PoS)consensus mechanism faces the threats of nothing at stake and long range attacks.To this end,this dissertation researches on the security issues of PoS consensus,designs a regulatory mechanism based on consortium chain,and builds a secure PoS consensus algorithm based on hardware module,to prevent the consensus against nothing at stake,long range and double-spending attacks.By setting the root of stakes to participate in competitions,the security of consensus within sharding blockchain network are ensured.Experimental results show that consensus latency reduces by multiple orders of magnitude and transaction processing efficiency enhances more than twice compared to existing secure consensus schemes,besides,the regulatory mechanism is highly efficient.3 Dynamic and efficient consensus message broadcast protocol to strengthen secure consensus:Blockchain nodes propagate messages to the entire network through a Peerto-Peer(P2P)communication network,resulting in problems such as large network resource consumption,high propagation delays,large message traffic and low delivery ratio.In practical public blockchain applications,mobility of nodes increases difficulty of message propagation.To this end,this dissertation researches on the problems of efficiency and uncontrollable node mobility of consensus message broadcast protocols.In the network topology model based on social characteristics of nodes,multicast technology is used to realize message propagation to save travel hops and achieve high delivery ratio.The message propagation technology improves the PBFT-based consistency protocol,thus,no controlling of nodes mobility is needed during the complete consensus message broadcast.Experiments based on the blockchain simulator show that the protocol improves the transaction processing efficiency,reduces the consensus delay(1/3～1/2)and promotes the consistency level(10%)of blockchain systems.4 Secure simplified payment verification-supported space saving blockchain transaction storage mechanism:Blockchain preserves all historical transactions and the data as a credible proof cannot be arbitrarily deleted,resulting in large storage overhead.The blockchain storage mechanism determines the possible transaction privacy leakage risk during Simplified Payment Verification(SPV).To this end,this dissertation researches on the space overhead of blockchain storage and the user privacy leakage during SPV,designs an index construction algorithm to realize transactions hiding,builds a transaction storage structure with low storage based on the Coloring Embedder,and implements the privacy preservation and space saving of the main chain storage of blockchain.Thereby,it solves the problem that the existing low storage overhead mechanisms destroy the distribution and integrity of blockchain.Experimental based on the blockchain simulator show that the mechanism is applicable to existing blockchain systems,and saves about half space of the other solutions.