attribute-based cryptography

Remote data auditing (RDA) protocols enable a cloud server to persuade an auditor that it is storing a data file honestly. Unlike digital signature(DS) schemes, in RDA protocols, the auditor can carry out the auditing procedure without having the entire data file. Therefore, RDA protocols seem to be attractive alternatives to DSs as they can effectively reduce bandwidth consumption. However, existing RDA protocols do not provide adequately powerful tools for user authentication. In this paper, we put forward a novel attribute-based remote data auditing and user authentication scheme. In our proposed scheme, without having a data file outsourced to a cloud server, an auditor can check its integrity and the issuer’s authenticity. Indeed, through a challenge-response protocol, the auditor can check whether 1) the cloud server has changed the content of the data file or not; 2) the data owner possesses specific attributes or not. We show that our scheme is secure under the hardness assumption of the bilinear Diffie-Hellman (BDH) problem.