International Association
for Cryptologic Research

Template Attack is widely accepted to be one of the most powerful side-channel attacks, because it is assumed that one has full knowledge of targeted crypto devices and thus be well capable of characterizing the side-channel leakages. However, whether or not Template Attack exploits side-channel leakages to the fullest is still not clear. In this paper, we present a negative answer to this central question, by introducing a normalization process into original Template Attack. We present Normalized Template Attack, which has the normalization process. Furthermore, we prove that Normalized Template Attack is better that its original counterpart in terms of leakage exploitation rate. We evaluate the key-recovery efficiency of Normalized Template Attack and original Template Attack as well under identical scenarios, by performing attacks against both simulated and real power traces. Our experimental results show that our method is valid end effective. Remarkably enough, this normalization process is of extremely low computation cost. Therefore, we argue that the

normalization process should be integrated as a necessary part of profile attacks in order to better understand the practical threats of these attacks.