Research On Audit Method Of Shared Cloud Data

Cloud storage is a new technique for storaging data on the cloud.Through cloud storage services,users can not only store data on the cloud conveniently,but also share data in a group.To ensure the integrity of the shared cloud data,the third-party auditor can be used to verify the integrity of the data,but in the process of auditing,the third-party auditor can access to the identity of the group members through the signature of block.Although existing research work on shared cloud data can not only solve the problem of data block identity protection in public auditing,but also support the dynamic change of groups.However,such schemes unable to track the identity of group members who modify the data maliciously.Moreover,when users upload the cloud data and update a large number of cloud data,it brings heavy online burden for hardware-limited mobile client to sign data blocks.Especially for fine-grained dynamic data update,the present approach not only requires the user to calculate the signature of new data block,but also need the cloud server returns the old block,which generate large amount of computation and communication.In view of the above shortcomings,Firstly,we proposes a shared cloud data audit scheme(ASDA)supporting user traceability and lightweight,with blind signature technology and dynamic broadcast technology,While protecting the privacy of user data,the user's computation amount is reduced.Moreover,on the security-mediator,the information of group users which can achieve traceability is saved in the form of data traceability table.The experimental data show that the calculation and communication overheads of the clients in ASDA scheme is greatly reduced,and the traceability of the identity of shared cloud data can be realized.Secondly,we improve the shortcomings of current fine-grained update scheme,using the data of blind technology and proxy signature technology,Security-mediator can be used to deal with the fine-grained update instead of users,so during the update audit process,the user can be off-line,thereby reducing the communication cost and the computational overheads at user side.Because of fine-grained updates is always essential in shared cloud data applications,this paper proposes a scheme named BTDA which introduces the improved fine-grained update scheme into ASDA to support fine-grained update.The experimental data show that compared with the current fine-grained updating scheme,BTDA has a large reduction in both computation overheads and communication cost at user side.