Exploration of the CC-EMA attack towards efficient evaluation of EM information leakage

This paper discusses the efficiency of the CC-EMA (Clockwise Collision based ElectoroMagnetic Analysis) attack on hardware implementation of 128-bit AES (Advanced Encryption Standard) block cipher. The analysis efficiency of CC-EMA was first discussed on a white-box setting, i.e., using a known-key AES (Advanced Encryption Standard) hardware [10]. Then, more realistic attack scenario was applied for CC-EMA, where the secret key of AES hardware was unknown, i.e., black-box analysis, and the attack efficiency in the key recovery was briefly discussed in [11]. In this paper, we revisit the previous work for CC-EMA and explore the attack efficiency of CC-EMA furthermore in order to evaluate the information leakage from proximal EM measurements of IC (Integrated Circuit) devices. In order to evaluate the attack efficiency under various attack environments, we construct a simulation environment, where the intensity of EM radiation is parameterised assuming that it follows a normal distribution. As a result, we show that CC-EMA attack delivers equal or superior performance in the key recovery compared to the CEMA (Correlation EMA) attack and the key can be recovered by CC-EMA with less than 1100 EM measurements, in such case that the EM intensity for CC could be measured distinctly.