A Novel Blockchain Consensus Protocol Based On Proof-of-transactions And Its Application

Blockchain is a kind of distributed ledger that can transmit credible information and realize value transfer in untrusted networks.It is one of the most revolutionary emerging technologies in recent years.Blockchain technology is widely applied in the fields of finance,government af-fairs,traceability,Internet of things,copyright protection and so on.However,the development of blockchain technology is facing the key technical bottleneck of scalability.This dilemma makes the blockchain consensus protocol,the key technology of scalability improvement,be-come the current research hotspot.There are some deficiencies in the existing consensus protocols,which can not meet the needs of the development of blockchain.The Po X-type consensus represented by Proof of Work(Po W)can ensure the final consistency,but it has the disadvantages of low performance and high energy consumption.On the contrary,the BFT-type consensus represented by practical Byzantine fault tolerance protocol(PBFT)and the traditional distributed consensus algorithm represented by Raft achieve high performance,but sacrifice part or all of decentralization at-tribute.Aiming at the current situation that the existing consensus protocols can not address the requirements of scalability,fairness and security,this paper proposes a novel blockchain con-sensus protocol named Proof of Transactions(Po T).The most distinctive feature of Po T lies in that is that the valid transactions collected by consensus nodes are used as proof of their work.Po T divides the consensus process into two stages: the primary node election stage and the new block synchronization stage.And it realizes the consensus of the cluster on the new blocks in two rounds of communication time.In the primary node election stage,consensus nodes pre-construct new blocks,then broadcast the proof messages corresponding to their blocks,which contain the quantity of collected transactions,to the others.After a round of proof message exchange,the node with the most transactions is recognized as the primary node.In the new block synchronization stage,the consensus nodes check the new block from the primary node with the help of cached proof message,and finally receive the valid new block to their local blockchain.In addition,Po T also designs a logical clock mechanism based on block timestamp and a seed node mechanism to assist consensus nodes to confirm new blocks.In this paper,the proposed consensus protocol is implemented as modular software,and the cluster operation experiments are carried out under the conditions of normal operation of nodes,node collapse and node evil.It proves the consistency,availability and security of Po T.At the same time,this paper also demonstrates that the protocol has the advantages of good scalability,configurability and fairness.Furthermore,aiming at the problems of imperfect function,patient data security and pri-vacy risk in the existing data management and trading schemes of medical Internet of things system,this paper presents a sensitive data trading system named Ecare.In Ecare,Po T protocol is applied to solving the scalability problem of blockchain system in large-scale network.Ecare considers the functional requirements of data storage,remote diagnosis and data trading among the four participants of hospital,doctor,patient and research institution.It also integrates five layers of data access control mechanism,including data encryption,identity control,credit con-trol,proxy query and data authorization.The proposed scheme well meets the requirements of high performance,scalability and security of the system,and fully considers the control right of ordinary users to their own medical data.To sum up,this paper proposes a novel blockchain consensus protocol which integrates the advantages of single type consensus,such as Po X-type consensus and BFT-type consensus,and designs,analyzes,implements,tests and applies it.This paper provides a new solution for the scalability bottleneck of blockchain,which is conducive to the application and development of blockchain in large-scale systems such as the Internet of things.