Securely Outsourcing of Bilinear Pairings with Untrusted Servers for Cloud Storage

With the cloud storage services, users can easily form a group and share data with each other. Public auditing scheme for shared data (PASSD) allows users or a third party to verify the integrity of the shared data in the cloud. However, the verification process of PASSD needs to compute a substantial number of bilinear pairings, which are also the fundamental of many other cryptographic protocols. In this paper, we propose a generic protocol to securely outsource a series of bilinear pairings to untrusted cloud servers. Moreover, we apply our generic protocol to a typical scheme of PASSD to speedup its verification process. The numerical and experimental analyses demonstrate that the proposed scheme significantly outperforms multiple runs of up-to-date delegation schemes for single bilinear pairing and achieves great efficiency gain for the client side, which makes the PASSD schemes more feasible for mobile computing environments.