Experimental Identification of Relationship between Leakage Trace SNR and Correlation Coefficient in Differential Power Analysis
Yusuke Yano, Toshiaki Teshima, Kengo Iokibe, Yoshitaka Toyota · 2019
A purpose of this work is providing a SCA resistance evaluation method that can associate the evaluation result with design criteria of countermeasure circuits at the system level. A method evaluating the SCA resistance of cryptographic circuits based on the signal-to-noise ratio (SNR) of the side-channel trace is examined. Here, it is assumed that SNR is used as SCA resistance design targets and the targets are determined based on analytically derived relationship between the SNR and correlation coefficients calculated in SCA. This work has experimentally verified that the SNR and correlation coefficients calculated from measured side-channel traces satisfy the relationship. A printed circuit board (PCB) with a field-programmable gate array (FPGA) implementing an advanced encryption standard (AES) circuit was used as an equipment under test, and the core power supply voltage fluctuation of the FPGA was measured on the PCB as side-channel trace. The SNR is calculated using a signal component obtained from the trace when encrypting a random plaintext set and a noise component obtained from the trace when encrypting a constant plaintext set. The correlation coefficient is calculated based on the correlation power analysis. The SNR was changed in the range of 20 dB by changing measurement conditions, and the relationship was examined. As a result, the SNRs and the correlation coefficients of the measured trace obeyed the analytical relational expression.