Comparing Sboxes of ciphers from the perspective of side-channel attacks

Side-channel attacks exploit physical characteristics of implementations of cryptographic algorithms in order to extract sensitive information such as the secret key. These physical attacks are among the most powerful attacks against real-world crypto-systems. This paper analyses the non-linear part (called Sboxes) of ciphers, which is often targeted by implementation attacks. We analyse Sboxes of several candidates that were submitted to the competition on authenticated encryption (CAESAR) as well as several other ciphers. We compare theoretical metrics with results from simulations and with real experiments. In this paper, we demonstrate that, in some contexts, the theoretical metrics provide no information on the resiliency of the Sboxes against side-channel attacks.