Research And Application On Certificateless Searchable Encryption Scheme

As the development of cloud computing and the spread of network security knowledge,the privacy and security of data has become the focus of users' attention.However,users directly upload ciphertext to the cloud will cause that cloud server faces the issue of data retrieval difficulties.Searchable encryption technology enables users to search encrypted data directly,which contents the demands of users to store and search encrypted data in the cloud.But,in the traditional public key cryptography environment,searchable encryption schemes generally suffer certificate management and key escrow problems,and are vulnerable to offline keyword guessing attack from inside or outside malicious adversary.In medical data sharing application environment,due to the medical data contains the user's identity privacy information,the traditional searchable encryption schemes have been unable to guarantee the user's identity privacy security.To attack the above issues,this paper based on certificateless cryptosystem studies specific searchable encryption schemes for multi-user scenarios,medical data sharing scenarios and blockchain scenarios,the detailed research content is as follows:(1)In view of the problems that the current searchable encryption schemes are not able to support multi-user searching,and there is the risk of offline keyword guessing attack,certificateless searchable encryption scheme for multi-user is designed.Under the certificateless cryptosystem,the scheme can avoid the complicated certificate management and key escrow issues,and satisfy the demands of multiple users with retrieve permission to search specific keyword ciphertext through the cloud server,and achieves the management of user rights by using the authorized key.In addition,by introducing the data owner's private key into the keyword encryption algorithm,the scheme can resist the inside keyword guessing attack.The scheme is more secure and efficient than existing related schemes.(2)In view of the problems that the current medical data sharing schemes are not able to protect the identity privacy of patients effectively,certificateless deniably authenticated encryption with keyword search for medical data sharing is constructed.The scheme uses deniably authenticated technology,which contents the demands of medical institutions and doctors to verify data sources,while the third-party organizations have no way of knowing where the data belongs,and better protect the identity privacy of patient.The result analysis shows the scheme contents the indistinguishability of ciphertext and trapdoor,as well as the unforgeability under deniable authentication.(3)In view of the problems that the data in the existing searchable encryption schemes may be tampered and forged,and the traditional blockchain cannot support the user's identity privacy-preserving verification,deniably authenticated searchable encryption scheme based on blockchain is introduced.By using the designed cloud server to save and search the ciphertext,and the blockchain stores signature verification information,the scheme ensures that the efficient storage and non tamperability of the data,and also avoids the block's own storage restrictions.Compared with related schemes,the scheme can provide effective identity privacy-preserving verification,and is more suitable for medical data sharing applications.