Research On Blockchain-Based Medical Data Sharing Scheme

The rapid development of technologies,such as cloud computing,Internet of Things(IoT)and 5G and other technologies has provided technical possibilities to solved the problem of medical information silos,promoted medical data sharing and facilitated the modernization of public health governance.In addition,the sharing of medical data can save medical resources,optimize the system architecture,and improve the efficiency of treatment.However,the existing data sharing mechanisms have been frequently compromised,violating patients’privacy and threatening their property and personal security.Attribute-based encryption,a public key encryption scheme that supports fine-grained access control,increases the data owner’s control over the data while protecting the data security.At the same time,the distributed and decentralized properties of blockchain bring great advantages to medical data storage and sharing.However,the computational shortcomings of existing attribute-based encryption mechanisms,the limitation of blockchain storage capacity,and the computational pressure of lightweight devices have led to inefficient data sharing in healthcare systems.In addition,malicious persons injecting malicious data into the blockchain not only mislead doctors’ diagnosis,but also disrupt public order and endanger patients’ lives in serious cases.The main work of this thesis is to investigate the above problem as follows:1.A blockchain-based solution for secure data sharing of personal health records was constructed to address the risk of privacy data leakage,fair retrieval of encrypted data,and limited computing resources of lightweight devices such as IoT in the process of medical data sharing.The solution uses CP-ABE(Ciphertext-Policy Attribute-Based Encryption)to encrypt data,and patients can control access to data users by setting access policies so that only users who meet the conditions can access the data.For devices with limited computational resources,online/offline encryption and outsourced pre-decryption techniques are used to reduce computational effort.At the same time,smart contracts are used to perform keyword search algorithms to improve the retrieval efficiency of target data.In addition,the traceability algorithm is used to detect malicious nodes in the blockchain retroactively.Performance analysis shows that this scheme has significant advantages over existing schemes[53],[65],[66].2.The redactable blockchain data sharing scheme with hierarchical access control is constructed to address the problem of malicious users injecting illegal data into the blockchain.The scheme uses the chameleon hash function to replace the original collision-resistant hash function in the blockchain,and authorizes the modifier to have the trapdoor key of the chameleon hash function to be able to re-write the blockchain data.In response to the problem of modifier’s power control,we adopt the hierarchical CP-ABE algorithm to realize the hierarchical control of the authorizer,reduce the power of the authorizer,and authenticate the modifier by digital signature to ensure the smooth and secure operation of the system.Based on DBDH,DCDH and CDH assumptions,the CPA(Chosen-Plaintext Attack)security,collision resistance and unforgeability of this scheme are proved.The performance analysis shows that the efficiency of this scheme is better than the existing schemes[17],[20],[45].