Improving CPA Attack Against DSA and ECDSA

In this work, we improved Correlation Power Analysis (CPA) attack against Digital Signature Algorithm (DSA) and its various derivations, such as Elliptic Curve Digital Signature Algorithm (ECDSA). The attack is aimed against integer multiplication with constant secret operand. We demonstrate this improvement on 16-bit integer multiplier in FPGA. The improvement makes it possible to guess more blocks of key, and the improvement also eliminates errors of simulated attacks what is very important when approximating attack success rate and complexity based on simulated attacks. We also discus a possible efficient countermeasure.