A Fast Implementation of Computing the Transparency Order of S-Boxes

Prouff has introduced, at FSE2005, the notion of transparency order of S-Box. This characteristic is related to the ability of an S-Box to thwart DPA attacks. In this study, we present a fast implementation method of computing the transparency order of S-Box. Our method introduces an elaborately-devised threshold filter which aims to minimize the unnecessary loops in the computing. Meanwhile, two optimization techniques are presented to further accelerate the computing. Our experiments show that it takes only 2.15 seconds by the trivial method to compute the transparency order of a 12 times 12 S-Box, while it takes 22161.92 seconds by our method, which is about 10, 356 times faster to do the same job.