Research On Cloud Data Sharing Scheme Based On Blockchain And Attribute-based Cryptography

Medical data sharing can improve the accuracy of patient treatment and promote the development of medical research institutions.However,it is easy to cause some security problems in the process of medical data sharing.First of all,patients may go to different hospitals for different symptoms,causing medical data to be scattered and stored in different medical institutions,causing patients to lose control of medical data,which is not conducive to medical data sharing.Secondly,medical data contain the patient's private information.If the patient authorizes a medical institution to outsource the medical data to a cloud server for storage,it is easy to cause data tampering and privacy leakage when it is maliciously attacked.Finally,malicious medical institutions and semi-trusted cloud servers may conspire to tamper with medical data,threatening the integrity of medical data.On the basis of the above questions and the analysis of the research status at home and abroad,this thesis mainly studies the blockchain-based medical data sharing cryptographic scheme.The details are as follows:(1)We propose a medical data sharing privacy protection scheme based on blockchain.The medical data ciphertext are stored in the cloud,and the storage address and medical-related information are written into the blockchain,which can ensure efficient storage and eliminate the possibility of irreversible modification of the data.The use of attribute-based encryption ensures that medical data are accessed by authorized users.It reduces the computational burden of data visitors by combining with the outsourcing decryption mechanism.(2)A blockchain-based medical data search and sharing scheme is proposed.The use of attribute-based searchable encryption technology ensures the safe storage of medical data in the cloud,and at the same time meets the needs of users to retrieve the ciphertext of medical data.The introduction of strategy hiding ideas prevents attackers from obtaining sensitive information and ensures the privacy and security of user identity;the use of a public audit mechanism verifies the integrity of cloud medical data.The proposed scheme achieves a constant ciphertext length,and has lower storage cost and computational overhead compared with similar schemes.(3)A verifiable medical data sharing scheme based on blockchain is proposed.It ensures the confidentiality of sensitive medical data and supports anonymous identity verification.The ciphertext length of the medical data is constant,and the storage overhead is reduced.At the same time,the use of outsourcing computing technology allows most of the calculations to be performed by cloud servers,which eases the computing burden of users.In addition,the proposed scheme is proved to have strong security in the standard model,and has better performance compared with similar schemes.