Efficient Exploitation of Noise Leakage for Template Attack

Because of its strong leakage characterization ability and high-key-recovery efficiency, template attack (TA) is the strongest side-channel attack from the information-theoretic point-of-view. In light of this, TA can be used as a powerful tool to evaluate the security of a crypto device in real scenarios. In fact, by evaluating the key-recovery efficiency of TA, the security of a crypto device can be quantified. Therefore, it is very meaningful to optimize the key-recovery efficiency of TA in real scenarios. In this work, we show that the leakage exploitation style can significantly influence the key-recovery efficiency of TA. In detail, rather than exploiting the leakage of the noise part, the leakage of the squared noise part can be used in TA. Theoretically, by exploiting the leakage of the squared noise part, the key-recovery efficiency of TA can be optimized under the normalized difference metric. Empirically, with the evaluation data provided by DPA Contest and ASCAD, the key-recovery efficiency of TA can be optimized under the success rate metric. Overall, this contribution may help one to accurately evaluate the security of a crypto device in real scenarios.