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Abstract. When studying the DPA resistance of S-boxes, the research community is divided in their opinions on what properties should be considered. So far, there exist only a few properties that aim at expressing the resilience of S-boxes to side-channel attacks. Recently, the confusion coefficient property was defined with the intention to characterize the resistance of an S-box. However, there exist no experimental results or methods for creating S-boxes with a "good" confusion coefficient property. In this paper, we employ a novel heuristic technique to generate S-boxes with "better" values of the confusion coefficient in terms of improving their side-channel resistance. We conduct extensive side-channel analysis and detect S-boxes that exhibit previously unseen behavior. For the 4 × 4 size we find S-boxes that belong to optimal classes, but they exhibit linear behavior when running a CPA attack, therefore preventing an attacker from achieving 100% success rate on recovering the key.

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In this work we present a duplex-based authenticated encryption scheme Friet based on a new permutation called Friet-P. We designed Friet-P with a novel approach for cryptographic permutations and block ciphers that takes fault-attack resistance into account and that we introduce in this paper. In this method, we build a permutation fC to be embedded in a larger one, f. First, we define f as a sequence of steps that all abide a chosen error-correcting code C, i.e., that map C-codewords to C-codewords. Then, we embed fC in f by first encoding its input to an element of C, applying f and then decoding back from C. This last step detects a fault when the output of f is not in C. We motivate the design of the permutation we use in Friet and report on performance in soft-and hardware. We evaluate the fault-detection capabilities of the software and simulated hardware implementations with attacks. Finally, we perform a leakage evaluation.