Paper 2016/1127

Related-Key Impossible-Differential Attack on Reduced-Round SKINNY

Ralph Ankele and Subhadeep Banik and Avik Chakraborti and Eik List and Florian Mendel and Siang Meng Sim and Gaoli Wang

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.

Note: extend results to a 23 round attack