Efficient Modular Exponentiation Resistant to Simple Power Analysis in DSA-Like Systems

In this paper, based on the concept of asynchronous strategy, we propose a new novel method to compute modular exponentiations against simple power analysis (SPA) in DSA-like schemes. Since the probabilities of digits in different detected computations are equivalent, the proposed methods are resistant to simple power analysis. Based on the SU1 method of asynchronous strategy, an efficient SPA-resistant method is proposed and has expected time complexity nS + 0.667nM (???1.467nM), where n, S, and M are the number of digits, squaring and multiplication, respectively. Although the performance can be further improved by using signed-digit representations, the security is reduced because of the non-equivalent probabilities of digits.