Experimental Investigation of Side-Channel Information Leakage from Printed Circuit Board with Split Ground Planes

Side-channel attacks, which break encryption by analyzing the physical behavior leaked from cryptographic devices, have become information security threats. This paper experimentally studied a standard evaluation board for side-channel attacks, SASEBO-G, and identified the source of side-channel information leakage superimposed on the common-mode (CM) current. Regarding the source of the CM current, we examined the effects of split ground planes for cryptographic and control FPGAs and an imbalance difference between SASEBO-G and power cables. We observed CM currents flowing through the cables. The correlation power analysis was performed by changing the separation of the ground plane and the amount of mode conversion caused by the imbalance difference. As a result, the CM current and information leakage intensity varied significantly depending on the ground plane separation. The ground separation on SASEBO-G is a potential cause of side-channel information leakage superimposed on the CM current.