Research On Electronic Medical Records Sharing And Privacy Preservation Based On Blockchain

With the popularization of medical care and the advancement of information technology,the medical industry has shown a tendency towards informatization and intelligence.Electronic Medical Records(EMRs),as the core content of medical service informatization,record the raw data in the whole process of medical diagnosis and treatment,and are highly valued by hospitals and doctors.In recent years,the world has been calling for frequently sharing of EMRs among medical institutions for information connectivity,which will benefit the clinical services,hospital development,medical research,etc.,and thus promote the prosperity of the entire healthcare industry.Therefore,the sharing of EMRs has become a research hotspot in the current medical information age,and intelligent healthcare will be within sight.However,at present,EMRs are mostly stored in various centralized medical institutions,which makes them easy to suffer from single-point attacks that may lead to data leakage or loss.Moreover,this data storage pattern causes a serious problem of “information island”,in which it is difficult to properly use and share EMRs.In addition,the interoperability between different providers and medical systems challenges the effectiveness of data sharing.Fortunately,due to the advantages of decentralized,highly redundant storage and tamperproof,the emerging blockchain technology privodes an opportunity to develop secure and reliable EMR distributed management and sharing systems.Via blockchain,the complete health history data of patients can be recorded and shared among different institutions.However,although blockchain has brought the opportunities for the medical field,the combination of them is still plagued by privacy and security issues.Therefore,it is prerequisite to design a privacy-preserving EMR sharing scheme for the application of blockchain in the medical field.Firstly,this thesis takes EMR sharing as the research background and summarizes the current status and the shortcomings of the traditional centralized storage mode.Subsequently,this thesis introduces blockchain technology and analyzes its technical features and application value in the medical field.Morever,aimed at the problem of the privacy preservation in the secure sharing of EMRs based on blockchain,this thesis adopts content extraction signature(CES)and analyzes the characteristics and applicability of CES scheme in electronic medicalscenarios.Secondly,based on elliptic curve cryptosystem,this thesis innovatively proposes a certificateless content extraction signature(CL-CES)scheme.The scheme realizes the extracted function of sensitive data in EMRs and meets the security requirements of unforgeability and confidentiality.Furthermore,the efficiency comparison and simulation results demonstrate that the scheme has obvious performance advantages and is suitable for the signing and extracting of large-scale EMRs in the medical scenarios.Finally,on the basis of the proposed CL-CES scheme,this thesis designs a privacypreserving data sharing protocol with blockchain for EMRs.Combining multiple technologies such as CES,cloud storage,and fabric consortium blockchain,the protocol has the characteristics of user anonymity,privacy preservation,data storage security,tamperproof,and unforgeability.Meanwhile,the protocol realizes efficient access and sharing of EMRs through the access control policy defined by the patient and implemented in the chaincode logic.This protocol adopts aggregate signature technology to merge multiple transaction signatures into a single one in the d BFT consensus process,which reduces the computational and storage overhead of transaction verification and improves the efficiency of the system operation.Besides,this thesis simulates and analyzes the protocol from three aspects: transaction verification time,throughput and fault tolerance.Simulation results show that the protocol achieves better performance and higher practical value in the medical and healthcare field.