Cryptanalysis of Reduced sLiSCP Permutation in Sponge-Hash and Duplex-AE Modes

Abstract

This paper studies security of a family of lightweight permutations sLiSCP that was proposed by AlTawy et al. at SAC 2017. sLiSCP also specifies an authenticated encryption (AE) mode and a hashing mode based on the sponge framework, however the designers’ analysis focuses on the indistinguishability of the permutation, and there is no analysis for those modes. This paper presents the first analysis of reduced-step sLiSCP in the AE and hashing modes fully respecting the recommended parameters and usage by the designers. Forgery and collision attacks are presented against 6 (out of 18) steps of the AE and hashing modes. Moreover, rebound distinguishers are presented against 15 steps of the permutation. We believe that those results especially about the AE and hashing modes provide a better understanding of sLiSCP, and bring more confidence about the lightweight version sLiSCP-light.