| The quality and safety of agricultural products is the fundamental guarantee for people's healthy lives,and the traceability system of the agricultural product supply chain is an important means to ensure the quality of agricultural products.The traditional traceability system of agricultural product supply chain is highly dependent on centralized servers.Once the server fails,the stored data will be lost.And in the process of spreading in the agricultural product industry chain,data sharing is not timely,which will easily lead to traceability information update speed can not keep up with the speed of data query.Therefore,the traditional traceability system of agricultural product supply chain needs to seek new technical solutions to solve the above-mentioned problems.Blockchain is a distributed ledger technology with core features such as decentralization,anonymity,tamper-proof and traceability.Therefore,this paper studies the blockchain technology and integrates it into the traceability system of the agricultural product supply chain.The overall design of the traceability system is carried out,and the two aspects of privacy protection and system operation efficiency are designed,and the prototype system is implemented and tested.Firstly,in order to realize the protection of transaction privacy data in the process of agricultural product supply chain traceability and a more fine-grained anti-tampering mechanism,this paper studies related cryptographic algorithms and proposes a proxy re-encryption-based agricultural product supply chain privacy protection scheme.In the original blockchain system,data is open and transparent.Malicious nodes in the system can obtain data and tamper with them through data analysis and other technologies,so that the data in the system cannot be well protected.This scheme introduces the proxy node as an intermediate party to transfer the transaction ciphertext,protects the content of the transaction between the authorizer and the authorized person,and makes it difficult for the attacker to obtain the link between the addresses of both parties in the transaction.It has been proved that the scheme has better performance through various proofs and analyses.Then,it analyzes the low efficiency and high latency of the PBFT consensus algorithm in the agricultural product traceability system,and proposes a low latency consensus algorithm LD-PBFT based on smart contracts.The algorithm first adds a candidate queue,and divides the nodes in the system into three categories: consensus nodes,master node candidate queue nodes and ordinary nodes.The consensus node is responsible for the consensus,the master node standby queue is responsible for electing the backup master node,the standby queue node is supplemented from the common node set,and the Byzantine nodes eliminated from the consensus set will also return to the common node set.The three types of nodes perform their duties while realizing the dynamic addition and deletion of nodes.Secondly,a voting mechanism for the contribution of nodes is added,and consensus nodes are selected from ordinary nodes through the contribution of nodes to ensure the quality of node selection.While the efficiency of view switching becomes higher,the Byzantine node is also reduced.Quantity.Finally,the consensus election strategy using smart contract technology is used to optimize the view switching protocol to prevent artificial cheating and voting behavior from causing the master node to become a Byzantine node to affect the efficiency of the consensus.Experiments proved that the LD-PBFT algorithm had lower latency and higher throughput.Finally,the above-mentioned encryption algorithm and consensus algorithm are implemented in the system,and the main functional modules are displayed and tested on the interface,which verifies that the system meets the needs of practical applications.This system has been running for one year in an agricultural product traceability company and has been affirmed by the company and customers. |
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