| With the continuous development of big data,artificial intelligence,cloud computing and other technologies,data has become a crucial factor of production,and it is imminent to develop the digital economy and break through the data sharing barriers between various fields.The scalability,low cost and flexibility of cloud services provide an important support for the development of data sharing.However,there are still some security issues that put user data at risk.These issues need to be resolved in further research on data sharing schemes.There are two main aspects: when searching for ciphertext through keywords,keyword information Leakage will seriously threaten the privacy of users.It is necessary to solve the data leakage problem caused by the collection and statistics of keyword information by the centralized semitrusted cloud server.Data owners control the flow of data through authority settings.In existing data sharing systems,data owners need to formulate complex access control strategies to ensure data security,integrity,and availability.Moreover,the execution of access control in most data sharing systems is placed on a centralized semi-trusted cloud server,which cannot ensure the correct execution of access control.This paper proposes an on-chain-on-chain collaborative data sharing scheme based on alliance chain smart contracts,which realizes the protection of ciphertext query privacy,rapid verification of user permissions,and permission changes without relying on trusted third parties.In this case,the correctness and credibility of the ciphertext data retrieval results are guaranteed.The three main research contents of this paper are as follows.(1)Aiming at the problem of using keywords to retrieve ciphertext data information leakage in the data sharing scheme,a keyword searchable encryption method based on alliance chain smart contracts is proposed.The improved Bloom Filter(IBF)is used to generate the original data keyword index and the search data keyword trapdoor,which protects the keyword privacy information.The original data is encrypted using CP-ABE base attribute encryption technology to ensure data security.The alliance chain smart contract technology is used to ensure the credibility,integrity and correctness of the ciphertext retrieval results.(2)Aiming at the problems of centralization of data sharing user access control execution process,high cost of user authority verification and modification,a method of MPT access control for private data based on alliance chain is proposed.Use Ethereum’s data storage technology(Merkle Patricia Tree MPT)to formulate user access control strategies to achieve data security protection and multi-user data sharing and improve the average response time of data sharing.The use of alliance chain smart contract technology can eliminate third-party intervention and improve interaction efficiency on the premise of ensuring data security.(3)Design and implement a data access control sharing system based on the above two points of research: the system solves the problem of key word information leakage when the data requester retrieves ciphertext data,and improves the ciphertext The retrieval efficiency of data prevents untrusted cloud servers from stealing private information of ciphertext retrieval keywords.Through the MPT user control strategy,the data owner can quickly verify the user’s access rights and change the rights. |
