A Blockchain-based Scheme For Privacy-preserving And Secure Sharing Of Medical Data

As the infrastructure of smart medical system,efficient storage and privacy protection of medical data play an important role in the medical field.However,medical data in medical institutions are mostly stored in a centralized way,which has many security risks.Once the central server is attacked,large-scale data loss will inevitably occur,which will lead to the privacy leakage of patients.In addition,due to the independence of different medical institutions,patients’ medical data cannot be safely shared,and third-party disease research institutions cannot obtain effective medical data for scientific research.Therefore,how to store the medical data safely and how to alleviate the contradiction between the patient’s data privacy and the medical data business needs of disease research institutions have become an important challenge for the smart medical system.In order to solve the problems,this thesis will propose a smart medical data storage and privacy protection scheme based on blockchain.Blockchain has the advantages of decentralization,distrust,anonymity,and non-tampering.It breaks through the limitations of traditional centralization-based technology,and has attracted the strong attention of financial,academic and industrial circles.Blockchain becomes a key technology to realize the secure storage and privacy protection of medical data.Firstly,aiming at the "single point of failure" problem exists in the traditional centralized data storage scheme,this thesis adopts the combination of database storage and blockchain technology to realize the storage mode of "on-chain" and "off-chain" of medical data.On the one hand,the patient’s medical data is stored in the existing cloud database,which avoids the whole system crash caused by the attack of a single server.On the other hand,the hash value of the medical data is stored on the blockchain for the data integrity inspection.Secondly,aiming at the problem of "supply and demand consistency" between data owners and data consumers.Namely,how to verify whether the medical data provided by patients meets the requirements of research institutions.This thesis utilizes zero knowledge proof technology to generate a credible zero knowledge proof based on the patient’s medical data.And it will be automatically verified through the smart contract without introducing a third party.If the verification is passed,this thesis adopts proxy re-encryption technology to convert the encrypted medical data of patients into the middle ciphertext that can be decrypted by research institutions,which realizes the medical data storage and privacy protection among patients,research institutions and semi-trusted cloud servers.In addition,considering that research institutions pay a certain cost in the process of medical data sharing,they expect to obtain the patient’s medical data exclusively.Therefore,this thesis records the transaction information between patients and research institutions in the blockchain network to ensure the commercial interests of research institutions.Finally,in the proposed that the theoretical method,this thesis realizes the prototype system of intelligent medical data storage and privacy protection scheme based on blockchain,and carries out function test,performance evaluation,security analysis,etc.based on this system,the final analysis results show that this scheme can meet the requirements of data efficient storage,security,integrity,traceability,privacy protection,and other requirements.