Improving Second-Order DPA Attacks with New Modeled Power Leakages

Higher Order Differential Power Analysis (HO-DPA) has been introduced for more than ten years. Various combining functions are applied to attack the masked AES implementation, but finding an appropriate combining function is still a big issue. We study the weakness of absolute difference method when using multi-bit variables to mount an attack. In this paper, an optimized method is proposed to improve its efficiency. Simulation results based on different combining functions show that the success rate of our method is twice as high as that of normal absolute difference and sum combining function. Our idea is also confirmed by physical traces measured on a FPGA platform.