Title: Related-Key Impossible-Differential Attack on Reduced-Round SKINNY
Abstract: At CRYPTO’16, Beierle et al. presented SKINNY, a family of lightweight tweakable block ciphers intended to compete with SIMON. SKINNY can be implemented efficiently in both soft- and hardware, possesses a Substitution- Permutation-Network structure, and supports block sizes of 64 and 128 bits as well as key and tweak sizes of 64, 128, 192, and 256 bits. This paper outlines a related-tweakey impossible-differential attack on 21 rounds of SKINNY-64/128 and two attacks on 22 and 23 rounds of SKINNY-64/128 under the assumption that 48 bits of the tweakey are public.