Towards Different Flavors of Combined Side Channel Attacks

Side Channel Attacks (SCA) have come a long way since first introduced. Extensive research has improved various aspects of SCA like acquisition techniques, processing of traces, choice of leakage model, choice of distinguishers etc. As a result, side-channel countermeasures have also improved. It is difficult to defeat such countermeasures and requires a huge number of traces. So far, only a few works studied the combination of SCA. In this paper, we put forward two methods to combine different attacks to accelerate SCA or to reduce the number of traces to attack. The first method is a combination of commonly used distinguishers. We provide a theoretical method and an empirical approach to combine Pearson and Spearman correlation coefficients. The second method suggests a combination of different measurements corresponding to the same activity. A metric to assess this combination using information theory is also given. Both methods are supported by application on real traces. The gain is expressed in terms of reduction in number of traces to attack. We report a gain of 50% for the first method and 45% for the second method.