Cryptology ePrint Archive: Report 2016/045

New Approaches for Secure Outsourcing Algorithm for Modular Exponentiations

Xi-Jun Lin and Lin Sun and Haipeng Qu and Xiaoshuai Zhang

Abstract: Outsourcing paradigm is one of the most attractive benefits of cloud computing, where computation workloads can be outsourced to cloud servers by the resource-constrained devices, such as RFID tags. With this paradigm, cloud users can avoid setting up their own infrastructures. As a result, some new challenges, such as security and checkability, are inevitably introduced. In this paper, we address the problem of secure outsourcing algorithm for modular exponentiations in the one-malicious version of two untrusted program model. We show that our proposed algorithm is more efficient than the state-of-the-art algorithms. On the other hand, we point out in this paper that the first outsource-secure algorithm for simultaneous modular exponentiations proposed recently is insecure, where the sensitive information can be leaked to the malicious servers. As a result, we propose a new and more efficient algorithm for simultaneous modular exponentiations. We also propose the constructions for outsource-secure Cramer-Shoup encryptions and Schnorr signatures which are also more efficient than the state-of-the-art algorithms.

Category / Keywords: implementation / secure outsourcing algorithm; modular exponentiations; one-malicious model

Date: received 18 Jan 2016

Contact author: linxj77 at 163 com

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Version: 20160119:132233 (All versions of this report)

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