Research On Security Technology In Blockchain-Based Medical Data Sharing System

As a kind of important carrier of medical data,electronic medical records are extremely valuable medical research materials.The efficient circulation of electronic medical records can promote medical big data service and promote the development of the medical field.However,the traditional centralized architecture of electronic medical records sharing system bring some shortcomings such as low efficiency and poor security.With the development of blockchain and cloud computing,these shortcomings have been greatly improved.Blockchain can realize the credible storage of medical data,realize the joint governance and maintenance of medical institutions,connect data islands together,and provide a more secure and efficient model for electronic medical record sharing,while cloud computing can solve the storage bottleneck of the massive medical data.However,electronic medical records usually contain sensitive information of patients.How to ensure the confidentiality of the data and the privacy of owners becomes a crucial issue.Therefore,how to protect the confidentiality of electronic medical records and the privacy of patients identity and provide a safe and reliable access control mechanism under the premise of achieving efficient sharing of electronic medical records is a very valuable research direction.In order to protect the user’s identity privacy in the electronic medical record sharing system,and trace the user’s real identity when malicious behavior is detected,an anonymous and traceable identity privacy protection mechanism which is suitable for distributed scenarios is proposed.The mechanism is based on a publicly verifiable threshold secret sharing scheme,which hides the real identity in the protection information,and distributes the secret to each consensus node in the medical consortium blockchain,and provides public information for everyone to verify shares.And then a pseudo-identity is provided for user as a legal identity in the system to protect its privacy.When a user exists malicious behavior,the shares of t consensus nodes are gathered to trigger the deployed smart contract to complete the traceability of the real identity.The innovation of this scheme is that users’ identity privacy not only can be protected by pseudo-identity,but also can be revealed when t consensus nodes ensure that it is a malicious node in spite of several corrupt consensus nodes are exist in blockchain.And a batch verification method is provided for everyone to verify all the shares efficiently.Finally,we conduct detailed analysis and proof of the correctness and security,and compared our scheme with reference schemes in performance.The result show that our scheme has better performance under the premise of ensuring safety.Then,in order to improve the efficiency of medical data sharing,solve the security threats and meet the security requirements of this scenario,protect the users identity privacy,and overcome the shortcoming,which is called collusion attack,of the other schemes,we also propose a safe and efficient electronic medical records storage and sharing scheme based on consortium blockchain.The anonymous and traceable identity privacy protection mechanism is utilized as a sub-protocol in this scheme to realize user identity privacy protection and conditional anonymous tracing.A novel “on-chain and off-chain” storage model combining blockchain and cloud is used to alleviate the storage pressure of massive medical data.We also use an improved proxy re-encryption scheme to ensure the confidentiality of electronic medical records in cloud server and to achieve the authorization to data visitors.Moreover,our scheme can resist the collusion attack of the semi-trusted cloud server and the data visitor and prevent them from conspiring to decipher electronic medical records that are not authorized to access.We analyzed and proved the safety of the scheme in detail,and compared our scheme with other schemes in both properties and performance.The analysis and simulation results show that our scheme not only has better properties and security,but also performs efficiently in sharing electronic medical records.