Theoretical and practical aspects of multiple samples correlation power analysis

Abstract

There is more than one sample in a power trace, corresponding to the process of the target intermediate value, which are known as interesting points. One can exploit the power leakages at multiple samples to recover the secret key used by the crypto device, and that is the idea of multiple samples correlation power analysis (MSCPA). Considering that the leakage exploitation of MSCPA is more efficient than that of correlation power analysis (CPA), the power of MSCPA should be stronger than that of CPA. We theoretically prove and practically verify this fact. Theoretically, we show the advantage of MSCPA over CPA in terms of the correct key distinguishing level. We show that compared with CPA, MSCPA enlarges the gap between the correlation coefficient computed under the correct key and the correlation coefficients computed under wrong key guesses, which makes the correct key easier to be distinguished. Practically, we evaluate the performance of MSCPA in real scenarios. Using power traces provided by DPA Contest v2 and v4.1, we compare the key-recovery efficiency of MSCPA with that of CPA. Experimental results show that compared with CPA, MSCPA can reach a higher key-recovery efficiency in the same scenario. Copyright © 2016 John Wiley & Sons, Ltd.