Cryptanalysis of Ascon

Abstract. We present a detailed security analysis of the CAESAR can-didate Ascon. Amongst others, cube-like, differential and linear crypt-analysis are used to evaluate the security of Ascon. Our results are practical key-recovery attacks on round-reduced versions of Ascon-128, where the initialization is reduced to 5 out of 12 rounds. Theoretical key-recovery attacks are possible for up to 6 rounds of initialization. More-over, we present a practical forgery attack for 3 rounds of the finalization, a theoretical forgery attack for 4 rounds finalization and zero-sum distin-guishers for the full 12-round Ascon permutation. Besides, we present the first results regarding linear cryptanalysis of Ascon, improve upon the results of the designers regarding differential cryptanalysis, and prove bounds on the minimum number of (linearly and differentially) active S-boxes for the Ascon permutation