| In the era of rapid development of the Internet and information technology,the construction of information electronic construction in medical institutions is also undergoing changes.Now,as one of the tools for storing medical information,the electronic medical record is gradually replacing the traditional paper medical record and becoming the first choice for medical institutions to store medical information due to its advantages of convenience,quickness and good sharing,of which the personal sensitive information has high practical value.The electronic medical record contains the patient’s private information.The attacker obtains the patient’s medical data by illegal means,which seriously violates the patient’s personal privacy.Traditional medical systems use a centralized method for data storage.Once problems occur in the central organization,it is easy to cause problems such as medical record data leakage and data tampering.And this centralized storage method makes it difficult to achieve data sharing and causes data utilization problems.In addition,patients do not participate in the management of their own private information,and they do not know when the private information is used.To solve the above problems,this paper proposes a block chain-based access control model for electronic medical records.The main research work is as follows:(1)Based on the role-based access control model,users are assigned roles and permissions are set.Different levels of access rights are set for visitors with different roles.Different roles have different information access rights to the same medical record privacy information.The access ability of visitors is controlled by setting information tolerance.In the access process,firstly,the visitor is authenticated,the access authority is verified,and the access request information is extracted and classified.Then the amount of information requested to be accessed is calculated for different levels of medical record privacy information and compared with the tolerance of information amount.When the established access control policy is satisfied,the request is responded.(2)The information entropy is combined with the access control of electronic medical records,and the information entropy formula is used to carry out hierarchical quantization processing on medical privacy information and calculate the amount of access request information.The visitor who meets the access control policy will not obtain the privacy information irrelevant to this visit,thus protecting the medical privacy data from excessive access and utilization,and objectively reflecting the rationality of the access control policy.The calculation process of information quantification is encapsulated into a block chain,and smart contracts are used to complete the calculation of the amount of access request information,thus reducing and saving the time cost of people and improving the operation efficiency.(3)Using the characteristics of the distributed ledger of the blockchain and its inherent encryption attributes can eliminate data isolated islands and promote data sharing among medical systems.Each visit will generate an access record and store medical data and access records on the blockchain.The decentralized nature of the blockchain makes it easier for patients to manage their own data and improves data sharing and privacy protection.And the records on the chain are permanent and cannot be tampered with,which makes every transaction information on the chain traceable.This model is designed and implemented in detail,and then the performance of this model is analyzed by means of access hypothesis analysis,security analysis,comparative analysis and experimental simulation.It can not only protect the user’s medical privacy information during the service process,but also allow patients to autonomously manage their own medical data,which is conducive to achieving privacy protection under medical data sharing. |
