Efficient outsourcing schemes of modular exponenti

Authors: Can Xiang Chunming Tang

Publish Date: 2015/01/15

Volume: 6, Issue: 1, Pages: 131-139

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Abstract

Modular exponentiation is one of basic operations among most of current cryptosystems In previous work in order to detect the dishonest behavior of cloud servers modular exponentiations can only be securely outsourced by using two untrusted cloud servers However these results cannot resist the collusion attack by the untrusted cloud servers In this paper we present two secure outsourcing schemes for modular exponentiations which enable users to securely outsource modular exponentiations to a single untrusted cloud server and detect the dishonest behavior of untrusted cloud server The first one is a secure outsourcing scheme for variable basevariable exponent modular exponentiation while the second is for simultaneous modular exponentiations Compared with other proposed schemes our outsourcing schemes are superior in both efficiency and checkability Moreover our schemes are secure without any cryptographic assumptions In addition we give two applications for our outsourcing schemes one is to construct an outsourcing scheme for Cramer–Shoup encryptions and the other is to design an outsourcing scheme for Schnorr signaturesThis work is supported in part by the National Natural Science Foundation of China under Grant No 11271003 the National Research Foundation for the Doctoral Program of Higher Education of China under Grant No 20134410110003 High Level Talents Project of Guangdong Guangdong Provincial Natural Science Foundation under Grant No S2012010009950 the Project of Department of Education of Guangdong Province under Grant No 2013KJCX0146 and the Natural Science Foundation of Bureau of Education of Guangzhou under Grant No 2012A004

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