Cryptology ePrint Archive: Report 2004/349

A DPA Attack on the Improved Ha-Moon Algorithm

Dong Jin PARK and Pil Joong LEE

Abstract: The algorithm proposed by Ha and Moon [HM02] is a countermeasure against power analysis. The Ha-Moon algorithm has two drawbacks in that it requires an inversion and has a right-to-left approach. Recently, Yen, Chen, Moon and Ha improved the algorithm by removing these drawbacks [YCMH04]. Their new algorithm is inversion-free, has a left-to-right approach and employs a window method. They insisted that their algorithm leads to a more secure countermeasure in computing modular exponentiation against side-channel attacks. This algorithm, however, still has a similar weakness observed in [FMPV04,SPL04]. This paper shows that the improved Ha-Moon algorithm is vulnerable to differential power analysis even if we employ their method in selecting $s_i$.

Category / Keywords: implementation / Ha-Moon algorithm, randomized exponentiation, side-channel attack

Date: received 8 Dec 2004, last revised 14 Dec 2004

Contact author: djpark at oberon postech ac kr

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Version: 20041215:042131 (All versions of this report)

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