Research On Secure Proxy Data Sharing System Based On Blockchain

Third party proxy services(such as cloud storage)bring a lot of convenience to data sharing.Users only need to upload data to the proxy server and share data by setting access control.Anyone with access rights can obtain data anytime and anywhere through the Internet.However,because the data is completely stored in the third-party agent,which also brings the problems of data security and privacy.The security of proxy data sharing is mainly divided into four aspects:data confidentiality,data access control,privacy protection and data integrity verification.Aiming at the above problems,this paper carries out research based on cryptography and blockchain technology.The main work is as follows:Firstly,for data security(including data confidentiality and access control)and user privacy,this paper proposes a proxy oblivious transfer scheme.The scheme extends oblivious transfer(two-party)to a proxy model(three-party)using proxy re-encryption and transfers the majority of work to the proxy.In this way,the scheme ensures both data security and user privacy.In the process of design,multiple mathematical tools are used to retain the characteristics of the two protocols such as unidirectional,collusion-resistant,etc.The security analysis shows that the scheme is more secure.Moreover,the performance analysis shows the feasibility of the scheme and also gives reference suggestions for practical application.Secondly,for data integrity verification,this paper proposes a dedicated virtual machine.The existing smart contract data verification method can not directly operate on the verified file object,which makes the size of contract bytecode very long.On the premise of ensuring security,this paper adds more operation codes related to the data verification scenario to the virtual machine,and designs the general file operation object to ensure the operability of the verified file in the virtual machine.While reducing the amount of contract bytecode,it also provides richer data verification modes to support the privacy and integrity requirements of proxy data storage.The performance analysis shows that the data integrity verification and other services provided by this scheme are feasible and efficient,which is conducive to a wide range of applications.Thirdly,to improve the business process,this paper designs and implements a complete secure proxy data storage and sharing system.The system model is designed according to the characteristics of blockchain,integrating the above work to form a complete system.The system mainly considers data sharing and verification services,and designs the interaction between business processes and entities.Finally,the analysis of the system shows the guarantee of security requirements in different dimensions and the improvement of efficiency.