Research On P2P Data Synchronization Mechanism For Light Computing Power Blockchain

With the development of the underlying technology of the blockchain,the application of the blockchain has entered the field of social notarization and intelligence and more and more light computing power blockchain projects are being implemented.Decentralization and trustless,the two major benefits of blockchain,are mainly based on the consensus mechanism and smart contracts.However,the P2 P network performance limits the further development of the light computing power blockchain.At present,the main factors restricting the performance of P2 P network of the blockchain are the transmission rate and transmission reliability.This thesis studied these two issues,and the specific work content is as follows:(1)Aiming at the insensitivity to delay and inflexible unchoke strategy of the traditional Bit Torrent protocol,this thesis proposed a delay-sensitive Bit Torrent data synchronization protocol DS-Bit.The improved work of the DS-Bit protocol mainly includes the pre-connection strategy and the DCTFT rule.The pre-connection strategy uses a timer in the Pre-Con-Info message to make the download peer send the request message in advance.Under the DCTFT rule,the interested peer choose the actual rate(taking into account the ratio of delay)rather than the transmission rate that the intersting peer onece offered as the reference.This thesis adopt mathematical methods to prove that the pre-connection strategy and DCTFT rule proposed are better than traditional Bit Torrent in the time of data synchronization and experiments show that the DS-Bit protocol greatly improves the data synchronization rate in P2 P network.(2)Aiming at the strong dependence on pre-trusted nodes and the difficulty of adapting to the dynamic changes of P2 P networks of the traditional Eigen Trust,an enhanced trust model DBTrust is proposed.The improvements we work includes the dynamic pre-trusted peer selection method,a trust value update method that the time influence factor introduced to,and a penalty measure to malicious peers based on the number of neighbors.DBTrust defines three types of services: malicious service,satisfactory service,and unsatisfactory service.The penalty coefficient is adjusted to strengthen the punishment for malicious services.Experiments show that DBTrust provides the system with more robustness.(3)Aiming at the severe challenges such as incomplete system,low degree of informatization and lack of effective regulatory measures faced by the cold chain of fresh agricultural products in China,this thesis combines the DS-Bit protocol and the DBTrust model proposed to design a blockchain service platform for assured fresh agricultural products.This thesis designed and implemented the system architecture,process and functional modules according to the overall requirements,and verifies the effectiveness of the system through system testing.