New Distinguishing Attacks on Round-Reduced Sparkle384 and Sparkle512 Permutations

The Sparkle permutation family is used as an underlying building block of the authenticated encryption scheme Schwaemm, and the hash function Esch which are a part of one of finalists in the National Institute of Standards and Technology (NIST) lightweight cryptography standardization process. In this paper, we present distinguishing attacks on 6-round Sparkle384 and 7-round Sparkle512. We used divide-andconquer approach and the fact that Sparkle permutations are keyless, as a different approach from designers' long trail strategy. Our attack on Sparkle384 requires much lower time complexity than existing best one; our attack on Sparkle512 is best in terms of the number of attacked rounds, as far as we know. However, our results do not controvert the security claim of Sparkle designers.