Research On Medical Data Sharing And Privacy Protection Based On Verifiable Outsourcing Encryption

In recent years,with the rapid development of social modernization,the informatization construction of smart medicine has attracted great attention in different countries.Furthermore,governments and companies have made some progress of intelligent medical system.Among various technologies of intelligent medical system,the research on electronic medical records(EMR)is a hot topic.With the emergence of cloud computing and edge computing,the current mainstream storage of electronic medical records are stored in a cloud server for data sharing.Data are stored in a public cloud server,which is required encryption to prevent privacy leakage.Usually,Attribute-Based Encryption(ABE),public key encryption,symmetric encryption,and proxy re-encryption are utilized to encrypt plaintext.Attribute-based encryption can provide fine-grained access control.However,in ABE,the finer the access control,the greater the number of attributes required.Therefore,it requires higher computational costs.In this paper,we mainly discuss how to outsource data and provide verification functions during data sharing,achieving the goal of reducing encryption burden.The first challenge is how to effectively check the correctness of outsourced ciphertext.Specifically,during the data sharing process,the edge server helps the data owner perform encryption tasks,and cannot allow the edge server to obtain the true data content.The data user also verifies the authenticity of the ciphertext.The second challenge is also to reduce the encryption burden on data owners,but the efficiency is better than the first issue.Specifically,the data owner formulates an access structure based on the Linear Secret Sharing Scheme(LSSS)and assigns an edge server to perform attribute related ciphertext calculations,where the edge server cannot obtain any valuable data.Furthermore,the ciphertexts returned from the edge server are submitted to the blockchain for verification.The main research contents of this paper are as follows.(1).An outsourced encryption scheme based on multiple encryptions is proposed,which provides checkability of the outsourced computation results in an efficient way.Firstly,using the hybrid encryption technique(i.e.,combining conditional public key encryption and attribute-based encryption),we can easily obtain fine-grained ciphertext tuples.And attribute-based encryptions are outsourced to the edge server,which is aimed to reduce the computing burden of the data owner.Secondly,the correctness of decrypted data is guaranteed through aggregate digital signatures.At the same time,using proxy re-encryption algorithm to achieve secondary authorization.Finally,experimental results and security proof show that our scheme has higher computational efficiency and achieves more fine-grained access control compared with other related schemes,while it ensures the security.(2).To further reduce data owner’s encryption overhead,a blockchainassisted outsourcing encryption scheme is proposed,which is intended to check the correctness after outsourcing encryption.Firstly,the symmetric encryption is utilized to replace the conditional public key encryption of the first scheme,and edge servers are adopted to calculate attribute related ciphertext to ensure finegrained data sharing,while reducing the encryption time of data owners.Secondly,using the blockchain consensus mechanism to verify the authenticity of the ciphertext calculated by the edge server.Finally,experimental results and security proof show that our scheme has higher computational efficiency than the first scheme,while it ensures the security.