Chosen-message electromagnetic analysis against cryptographic software on embedded OS

This paper presents an EMA (electromagnetic analysis) against an RSA software on an embedded operating system (OS) and its counter measure First, we describe a pre processing step to find an appropriate observation point for EMA, where the EM radiation caused by cryptographic operations can be observed in an accurate manner. We employ a specific input pattern, which is suitable for observing EM radiation according to an EM radiation model, and scan a micro magnetic probe on the tar get device in order to find specific EM radiation pattern for EMA. This preprocessing can be conducted on another programmable device that has the same CPU and OS as the target device We demonstrate that such EM analysis is effective for an RSA software per formed on Android OS. We also confirm the validity of a counter measure against the presented attack.