Information Theoretical Analysis of Side-Channel Attack

摘要

This paper presents a proposal of a new information-theoretical evaluation method for the side-channel resistance. This method provides some benefits: It provides a rationale for evaluation. Moreover, it enables numerical execution of mutual evaluation among countermeasures of several kinds. In an evaluation of side-channel resistance, the feasibility of attack, such as the number of observations or experimental time for revealing secrets, is discussed. In conventional methods, these numbers are examined experimentally using actual attacks. Therefore such experimental methods present several problems: (1) the rationale of the numbers used in evaluation is poor; (2) executing mutual evaluation is difficu and (3) some experimental constraints exist such as time, cost, and equipment specifications. Our proposed method regards side-channel attack as a communication channel model. Therefore, this method estimates its channel capacity as the upper bound of the amount of leakage information. As described herein, we apply this approach to correlation power analysis against implementations of stream cipher Enocoro-128 v2 and underscore its effectiveness.