Research On Privacy Protection Technology Of Medical And Health Data Sharing Based On Blockchain

With the digitization of information,the healthcare sector has ushered in the era of healthcare informatization.Healthcare data has been regarded as a valuable and tradable digital asset due to the sensitivity of its content and scientific research potential.Traditional healthcare data is stored through local databases or clouds and managed and shared by different organizations in a centralized manner,which has problems such as confusion in data management authority,lack of independent control of data by users and insufficient motivation to share,and can no longer meet the needs of the current healthcare environment.In contrast,blockchain technology,with its decentralization,non-tampering,anonymity,traceability,security and trustworthiness,programmability and collective maintenance,provides the feasibility of fine-grained access control while effectively sharing medical and health data.Therefore,it is important to study blockchain-based privacy protection technologies for healthcare data sharing.The main research work of this paper includes.（1）Introduces the research background and significance of blockchain-based privacy protection technology for healthcare data sharing,analyses the current status of domestic and international research from the perspectives of secure sharing and privacy protection respectively,and outlines the relevant theories and technologies such as the foundation of cryptography,blockchain technology,bilinear mapping,access control based on attribute encryption and searchable encryption.（2）To address the existing healthcare data sharing scenarios with cumbersome and inefficient sharing processes,information leakage and fair payment problems,a technical solution for secure healthcare data sharing based on smart contracts and dynamic pricing is proposed.By designing two scenarios of healthcare data sharing,smart contracts are used to achieve secure data sharing and arbitration dispute resolution.A dynamic pricing strategy for data based on willingness to share and willingness to buy is also proposed to give fair privacy compensation to data providers in different scenarios,respectively.By designing a simulation model of data transaction,we compare and analyze with related scenarios and analyze the impact of different parameters on the convergence of pricing.Meanwhile,the scheme is analyzed in terms of smart contract execution cost and execution efficiency,data integrity,shared confidentiality,and privacy vulnerability.（3）A fine-grained access control technology solution based on blockchain and reputation evaluation is proposed to address current problems such as users losing absolute control over data in access control.The encrypted healthcare data is stored in the IPFS distributed network,and the cryptographic information including decryption keys and storage addresses is published to the blockchain using smart contracts.By assigning keys to access users and dynamically giving them attribute permissions,only access users who meet the reputation threshold and whose attributes match the access policy can download and decrypt the data.The on-chain data is also stored using improved smart contract storage methods.The EOS blockchain is constructed for simulation experiments to analyze the computational overhead of different stages of the scheme.Also,the storage overheads before and after the improvement are compared and analyzed.Innovations in this thesis include.（1）A technical solution for secure sharing of healthcare data based on smart contracts and dynamic pricing is proposed.The scheme distributes medical health data off-chain for storage,and achieves automatic fair data delivery and data dispute resolution through smart contracts;uses smart contracts to publish download tokens to the blockchain to achieve timeliness of data sharing;uses a dynamic pricing strategy for data based on willingness to share and willingness to buy to achieve reasonableness and stability of data sharing in a dynamic environment;and uses a fair privacy compensation mechanism to stimulate the motivation of sharing healthcare data.Security analysis and comparative experiments show that the scheme has a significant advantage in sharing cost while ensuring data security,and can achieve price convergence in as few as five sharing interactions as the parameter k is reduced.It is suitable for secure,flexible and efficient distributed healthcare data sharing in environments lacking trustworthiness.（2）A fine-grained access control technology scheme based on blockchain and reputation evaluation is proposed.The scheme encrypts the original data and stores them on the IPFS distributed network,and uses smart contracts to store the decryption keys and corresponding hash addresses encrypted by CP-ABE on the blockchain to achieve distributed access control;uses user attributes to generate cryptographic keyword indexes to achieve privacy protection for accessing users during retrieval;uses reputation assessment to calculate the reputation value of users to promote active interaction between users to reduce the risk of mischief;in addition,improves the data storage method of smart contracts at the data upload stage to improve the efficiency of on-chain storage and reduce the storage execution overhead.In addition,the data storage method of smart contract is improved in the data upload stage to improve the on-chain storage efficiency and reduce the storage execution overhead.Simulation experiments and related comparative analysis show that with the increase of users changes also compare the computation time overhead to maintain a stable and acceptable interval,while the storage overhead of the smart contract with the increase of data volume,the cost reduction is more obvious,suitable for dynamic attribute permission revocation and fine-grained access control in a dynamic environment.