Research On Public Auditing In The Groups Without Managers

With the rapid development and widespread application of cloud computing and big data,more and more government agencies,businesses,and individual users tend to use the various applications provided by cloud servers to enjoy on-demand service.Among all kinds of convenience services,remote data storage is one of the most popular services.It not only greatly reduces users’ burden on local storage,but also provides users with storage services that not subject to time and space constraints.To ensure the integrity of cloud storage data and reduce the pressure of users on authenticate online,a third-party is introduced in public audit scenarios to operate the integrity verification on the stored data in clouds.Based on the existing public audit research,this thesis puts forward several integrity verification schemes for data storing and sharing in groups without managers.By utilizing the public audit technology,threshold signature technology,homomorphic encryption technology,attribute encryption technology,blockchain technology,etc.,the thesis aims to propose data storage and sharing service in groups with no managers.The main research results and innovation points are as follows.1.Considering the fact that the verification schemes for groups without managers cannot achieve identity equality or identity tracking at the same time,this thesis proposes two schemes that provide each member with equal power and allow members to trace identity by cooperation:Homomorphic Authenticable Democratic Group Signature and Public Auditing(HADGSP),which supports efficient auditing and Practical and Secure File Sharing(PSFS)with high security.HA-DGSP utilizes threshold technology to propose a signature with identity equality and traceability.Based on the signature,we construct a public auditing scheme with data privacy protection and non-frameability.The experimental results show that the overhead of auditing is independent of the number of group users.Based on the HA-DGSP scheme,the PSFS proposes an improved signature and an auditing protocol to protect identity privacy in auditing and the source of shared files during data sharing,which improve the security level.Theoretical analysis proves that PSFS achieves the following attributes: identity privacy protection,public audit,identity traceability and secure file sharing.2.For the data modification conflicts and group dynamic inefficiencies caused by dynamic operations in groups without managers,this thesis presents a Secure Cloud Data Sharing based on Blockchain and Public Auditing(Se Share)which is based on blockchain and public auditing,and a group dynamic protocol based on logic hierarchy tree.Se Share utilizes the idea of blockchain,convergence encryption and homomorphic encryption technology to ensure the uniqueness of shared files,resolve conflicts of modification,and enable efficient public auditing.The security analysis proves that Se Share is secure under the CDH assumption in the random oracle model.Besides,to achieve secure and efficient group dynamics in non-manager groups,we propose the method of logical hierarchy tree-based key updating to realize user joining and leaving.3.Considering the negativity of group members in non-manager groups during data sharing,this thesis propose two schemes: Incentive Public Auditing Scheme for Non-Manager Groups(IPANM)that utilizes threshold technology and blockchain to motivate users to participate in the generation of signature and Customized Data Sharing(CDS)that encourages file owners to share their files.IPANM combines the advantages of threshold signature,blinding technology and incentive mechanism to assign the same signing rights to users and encourages them to participate in the generation of signatures in order to generate the final signature as soon as possible.Performance analysis shows that IPANM is publicly audited,efficient,correct,unforgeable and robust.To allow file owner to customize access policy,CDS uses the knowledge of signature encryption based on attribute encryption,blockchain technology and weight attributes to propose a data sharing service.For the first time,the concept of customization is introduced in the field of public audit to increase the permissions of file owners.Security analysis proves that CDS has the following characteristics: correctness,data privacy-preserving,availability of access policy,and customization.