Novel Approaches for Improving the Power Consumption Models in Correlation Analysis

Differential Power Analysis (DPA) is a powerful technique for revealing secret data of cryptographic algorithms such as DES, AES and RSA implemented on a specific platform. In recent years, Correlation Power Analysis (CPA) allowed to better formalize the differential approaches of DPA with the use of a power model. We propose here two methods in order to optimize the power model for the targeted bits of the analysed algorithm. We will consider that all the targeted bits do not give the same contribution to the power consumption. Our first method consists in finding out the optimal ratio among the bits of a specific device. The second method is based on a statistical analysis of attack results while applying different possible ratios among the bits. The experimental electromagnetic radiation signals intercepted from an ASIC during DES operations show that our proposed methods allow to improve significantly the attack performance.