Research On Group Key Agreement And Group Data Sharing Protocol Based On Blockchain

In the era of big data,in order to ensure the security and convenience of mass data access,more and more people choose to store their valuable data in the cloud.However,the current cloud services are often maintained by a single service provider,and there is a risk that the information of all employees will be leaked once the central server is attacked.In addition,traditional cloud storage patterns depend on specific service providers,and multiple cloud services are often incompatible.This makes it difficult for organizations using different cloud services to share data.Blockchain technology provides solutions to these two challenges.Unlike traditional cloud storage architectures,blockchain is a distributed technology with multiple participants.Its data management is not solely dependent on either party,and the data cannot be tampered with once written,so there is no single point of trust.Secondly,blockchain itself is a global common ledger system with natural cross-domain and trust environment.It can well solve the platform compatibility problem of data sharing requirements between different cloud services.In this dissertation,starting from the two major problems: communication in the non-trusted Internet of things(Io T)environment with massive data and the medical environment that urgently needs to solve the data sharing,blockchain-based protocols suitable for its requirements are designed respectively.With the access of massive Io T devices,the current centralized system management structure has been unable to provide management and security maintenance for them.In order to ensure the security of group communication,this dissertation proposes a distributed group key agreement protocol with compatible security and high efficiency based on the blockchain technology,combined with the low energy characteristic of Io T devices.In the key generation stage,the protocol combines the heterogeneous characteristics of various devices in the Io T environment to conduct cluster and hierarchical processing of devices,greatly reducing the key agreement energy consumption of mass devices.In the key update stage,different key update strategies are developed through the intelligent contract mechanism,which can effectively guarantee the forward and backward security of group communication.Addressing the difficulty of sharing medical data,corresponding data sharing protocols were designed based on blockchain technology for the two business models ofnational hospitals at the same level and hospitals at the upper and lower levels.In the whole protocol design process,the patient's unique biological information and identity information are used to identify the relevant medical information.In the data sharing protocol between hospitals at the same level,each national hospital is regarded as a consensus node in the blockchain network,and all data sharing requests need to be verified by consensus from other hospitals at the same level.In the data sharing protocol between upper and lower hospitals,considering that the resource reserve of lower community hospitals is not enough,we use message list to verify the identity of the data requester,so as to realize partial data sharing.Compared with other relevant data sharing protocols,our protocol can guarantee the security of the data sharing party while guaranteeing the data sharing function.