Advanced Client Repudiation Diverge Auditor in Public Cloud
Ms.Nita R. Mhaske, Prof. S.M Rokade · IOSR Journal of Computer Engineering · 2014
With data storage and sharing services provided by cloud , people work together by sharing data as a group .After creating group and shared data in the cloud user in the group is able to access and modified and also share the latest updated data with the rest of the group .To ensure shared data integrity can be verified publicly, users in the group need to compute signatures on all the blocks in shared data.Different blocks in shared data are generally signed by different users due to data modifications performed by different users.For security reasons, once a user is repudiated from the group, the blocks which were previously signed by this repudiated user must be re-signed by an existing user.The straight forward method, which allows an existing user to download the corresponding part of shared data and re-sign it during user repudiation, is inefficient due to the large size of shared data in the cloud.In this paper, we propose a novel diverge auditing mechanism for the integrity of shared data with efficient user repudiation .By utilizing the idea of proxy re-signatures, we allow the cloud to re-sign blocks on behalf of existing users during user repudiation, so that existing users do not need to download and re-sign blocks by themselves.In addition, a public verifier is always able to audit the integrity of shared data without retrieving the entire data from the cloud, even if some part of shared data has been re-signed by the cloud.