Single Tweakey Cryptanalysis of Reduced-Round SKINNY-64

Abstract

SKINNY is a lightweight tweakable block cipher which received a great deal of cryptanalytic attention following its elegant structure and efficiency. Inspired by the SKINNY competitions, multiple attacks on it were reported in different settings (e.g. single vs. related-tweakey) using different techniques (impossible differentials, meet-in-the-middle, etc.). In this paper we revisit some of these attacks, identify issues with several of them, and offer a series of improved attacks which were experimentally verified. Our best attack can attack up to 18 rounds using$$2^{60}$$ chosen ciphertexts data,$$2^{116}$$ time, and$$2^{112}$$ memory.