Evaluation of (power) side-channels in cryptographic implementations

Abstract Side-channel attacks enable powerful adversarial strategies against cryptographic devices and encounter an ever-growing attack surface in today’s world of digitalization and the internet of things. While the employment of provably secure side-channel countermeasures like masking have become increasingly popular in recent years, great care must be taken when implementing these in actual devices. The reasons for this are two-fold: The models on which these countermeasures rely do not fully capture the physical reality and compliance with the requirements of the countermeasures is non-trivial in complex implementations. Therefore, it is imperative to validate the SCA-security of concrete instantiations of cryptographic devices using measurements on the actual device. In this article we propose a side-channel evaluation framework that combines an efficient data acquisition process with state-of-the-art confidence interval based leakage assessment. Our approach allows a sound assessment of the potential susceptibility of cryptographic implementations to side-channel attacks and is robust against noise in the evaluation system. We illustrate the steps in the evaluation process by applying them to a protected implementation of AES.