Efficient online/offline signatures with computational leakage resilience in online phase

  • Authors:
  • Fuchun Guo;Yi Mu;Willy Susilo

  • Affiliations:
  • Centre for Computer and Information Security Research, School of Computer Science and Software Engineering, University of Wollongong, Wollongong, NSW, Australia;Centre for Computer and Information Security Research, School of Computer Science and Software Engineering, University of Wollongong, Wollongong, NSW, Australia;Centre for Computer and Information Security Research, School of Computer Science and Software Engineering, University of Wollongong, Wollongong, NSW, Australia

  • Venue:
  • Inscrypt'10 Proceedings of the 6th international conference on Information security and cryptology
  • Year:
  • 2010

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Abstract

An online/offline signature scheme allows separation of its signing algorithm into offline phase and online phase. There have been many constructions in the literature, and they are provably secure under chosen-message attacks. However, it has recently been shown that this security notion is insufficient due to side-channel attacks, where an adversary can exploit leakage of information from the implementation of the signing algorithm. Regarding the implementation of online/offline signatures, we found that the online phase is much more critical than the offline phase. In this paper, we propose two efficient online/offline signature schemes. Our online phase is secure with unbounded leakage resilience as long as the assumption that only computation leaks information holds. Our constructions offer a very short signature length and they are efficient in the online phase with modular additions only.