Providing Privacy and Data Integrity in Dynamic Group Using TPA Over Cloud Computing

Abstract:- We propose Panda, a novel public auditing mechanism for the integrity of shared data with efficient user revo-cation in the cloud. In our mechanism, by utilizing the idea of proxy resignatures, once a user in the group is revoked, the cloud is able to resign the blocks, which were signed by the revoked user, with a re-signing key. As a result, the efficiency of user revocation can be significantly improved, and computation and communication resources of existing users can be easily saved. Meanwhile, the cloud, which is not in the same trusted domain with each user, is only able to convert a signature of the revoked user into a signature of an existing user on the same block, but it cannot sign arbitrary blocks on behalf of either the revoked user or an existing user. By designing a new proxy re-signature scheme with nice properties, which traditional proxy re signatures do not have, our mechanism is always able to check the integrity of shared data without retrieving the entire data from the cloud. Here we have to focus on data transmitted with secure manner and revocation in cloud in ope