In the Cloud computing era, users could have their data outsourced to cloud service provider (CSP) to enjoy on-demand high quality service. On the behalf of the user, a third party auditor (TPA) which could verify the real data possession on CSP is critically important. The central challenge is to build efficient and provably secure data verification scheme while ensuring that no users' privacy is leaked to any unauthorized party, including TPA. In this paper, we propose the first identity-based public verification scheme, based on the identity-based aggregate signature (IBAS). In particular, by minimizing information that verification messages carry and TPA obtains or stores, we could simplify key management and greatly reduce the overheads of communication and computation. Unlike the existing works based on certificates, in our scheme, only a private key generator (PKG) has a traditional public key while the user just keeps its identity without binding with certificate. Meanwhile, we utilize privacy-preserving technology to keep users' private data off TPA. We also extend our scheme with the support of batch verification task to enable TPA to perform public audits among different users simultaneously. Our scheme is provably secure in the random oracle model under the hardness of computational Diffie-Hellman assumption over pairing-friendly groups and Discrete Logarithm assumption.

cloud computing; storage security; identity-based; public verification; privacy-preserving

University of Electronic Science and Technology of China