Cluster Computing

, Volume 16, Issue 4, pp 787–796 | Cite as

Outsourcing computation of modular exponentiations in cloud computing

  • Xu Ma
  • Jin Li
  • Fangguo Zhang


Cloud computing is an emerging computing paradigm in which IT resources and capacities are provided as services over the Internet. Promising as it is, this paradigm also brings forth new challenges for security when users want to securely outsource the computation of cryptographic operations to the untrusted cloud servers. As we know, modular exponentiation is one of the basic operations among most of current cryptosystems. In this paper, we present the generic secure outsourcing schemes enabling users to securely outsource the computations of exponentiations to the untrusted cloud servers. With our techniques, a batch of exponentiations (e.g. t exponentiations) can be efficiently computed by the user with only O(n+t) multiplications, where n is the number of bits of the exponent. Compared with the state-of-the-art algorithm, the proposed schemes are superior in both efficiency and verifiability. Furthermore, there are not any complicated pre-computations on the user side. Finally, the schemes are proved to be secure under the Subset Sum Problem.


Modular exponentiation Outsourcing computation Security and privacy Cloud computing 



This work is supported by the National Natural Science Foundation of China (Nos. 61070168, 61100224 and U1135001), the National Basic Research Program of China (973 Program, No. 2012CB316100), and the Specialized Research Fund for the Doctoral Program of Higher Education, and the Foundation for Distinguished Young Talents in Higher Education of Guangdong Province (No. LYM10106).


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Copyright information

© Springer Science+Business Media New York 2013

Authors and Affiliations

  1. 1.School of Information Science and TechnologySun Yat-sen UniversityGuangzhouP.R. China
  2. 2.Department of Computer ScienceGuangzhou UniversityGuangzhouP.R. China

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