Research On Blockchain Consensus Scheme

Consistency is the most fundamental and important goal in a distributed system.Consensus algorithms are designed to achieve consistency.The earliest consensus algorithms,such as Paxos,VR,etc.,can tolerate up to f failures with 2 f + 1 main processors in harsh networking environments.They are widely used in distributed database systems.Practical Byzantine fault-tolerant algorithm(PBFT)proposed in 1999 tolerates up to f Byzantine faults with 3 f + 1 nodes in semi-synchronous networking environments.In2008,Satoshi Nakamoto proposed the first decentralized electronic cash system,Bitcoin.The underlying technology of Bitcoin is blockchain,which makes it possible to achieve consistency in open networking environments.In fact,the properties of blockchain technology such as decentralization/multi-centralization,high security,programmablility in business,etc.are very useful in a number of scenarios.Therefore,blockchain technology has attracted great attention from the government,industry and academia.As an important component of blockchain technology,the research on consensus algorithm becomes increasingly popular.A variety of consensus algorithms have been proposed.However,all of them have some limitations.For example,the Proof of Work(PoW)in Bitcoin can only process 7 transactions per second and is vulnerable to 51% attack and selfish mining.We anlyzed the mainstream consensus algorithms and summarize their key limitations: inefficient performance,inadequate security,and inflexibility in protocols.In order to provide a better solution,we propose a new hybrid consensus scheme with high performance,strong security and flexibility.Our research not only promotes the design of consensus algorithm,but also improves the availability of blockchain technology.The main contributions of this paper are as follows:(1)We proposed a novel hybrid consensus scheme named Goshawk,which has high performance and strong security.Goshawk consists of a two-level mining mechanism and a ticket-voting mechanism.Theoretically,the throughput of Goshawk is comparable to Bitcoin-NG.Further,Goshawk can resist 51% computation attack and selfish mining.The incentive mechanism designed in Goshawk incentivizes rational miners to comply with the rules,effectively inhibiting the malicious behavior of miners.(2)We implement in a real world blockchain project,and verify its performance and security on an open testnet.The throughput of Goshawk can exceed 1000 tps,which is comparable to that of VISA in magnitude.Therefore,Goshawk satisfies the requirements of many scenarios.(3)We design a smooth upgrade scheme in Goshawk,combining the upgrade of the protocol with the decentralized autonomy of the blockchain,making the decision of the protocol upgrade more fair.The upgrade process is also safer because it can prevent accidental hard forks caused by improper operation.