Research On Data Integrity Audit Technologies With Privacy Protection In Cloud Storage

With the continuous progress of Internet technology,the role of information technology in daily life is increasingly irreplaceable.As one of the core applications of information technology,cloud computing can reasonably allocate resources according to users' business needs,and provide users with services such as computing and storage.As one of the basic services and applications of cloud computing,cloud storage provides users with a large number of storage resources and flexible and convenient data management services,so as to reduce the pressure of resource shortage and management inconvenience caused by storing users' data locally.Therefore,more and more users outsource data to the Cloud Storage Server(CSS)to relieve the pressure of local storage.Because the CSS is not completely trusted by users,the integrity of the data stored in the CSS needs to be verified.In order to solve the untrustworthiness problem of the CSS,cloud storage integrity audit technologies have been proposed.The general approach of this technology is to introduce a special thirdparty organization for verification operation,which is called the Third-Party Auditor(TPA).However,most of the existing solutions still face very challenging problems.Inspired by the existing data integrity audit model in cloud storage,this thesis proposes two integrity audit schemes,focusing on user privacy protection and user revocation,and improving system efficiency and robustness.The work done is as follows:In order to solve the problems of identity privacy protection,user tracing and user revocation in data integrity audit in cloud storage environment,a traceable dynamic public auditing scheme with identity privacy preserving is proposed.The scheme realizes complete anonymity,which makes it impossible for a single user to know the identity of other users.Even if the CSS does not know the user's identity,it can also verify the legitimacy of the user's identity,thus hiding the user's real identity.At the same time,the scheme reconstructs the user's public key based on secret sharing technology,and reveals the user identity information corresponding to the tag by using not less than a specified number of legitimate user subsets,so as to achieve efficient user identity tracing.In addition,the scheme can update group key by constructing polynomial function.The efficiency and simulation analysis reflect the practicability of the integrity audit scheme.In order to solve the problems of third-party untrustworthiness,user revocation and user tag update in data integrity audit in cloud storage environment,a revocable and certificateless public auditing scheme is proposed.In this scheme,the user's private key is bound with the data to generate the tag,which is used to resist the forgery attack.At the same time,in the process of key generation,the idea of key exchange is used to enhance the robustness of the system,and hence the group manager can interact with the user through the public channel.In addition,the scheme supports key update of group users and tag update of revoked users.In this scheme,the group manager updates the key of the group user according to the number of revoked users,and the CSS uses the latest public key of the nonrevoked user and the number of revoked users to check the identity of the user,such that revoked users without the latest key cannot pass verification.Through the interaction among the CSS,the revoked user and the non-revoked user,the scheme can update the tags of the revoked user.Security proof and simulation analysis show that the scheme achieves efficient data integrity audit while ensuring security.