Improved higher order differential attack and its application to Nyberg-Knudsen's designed block cipher

Since the proposal of differential cryptanalysis and linear cryptanalysis i n 1991 and 1993. respectively, the resistance to these cryptanalysis has be en studied. In FSE2, Knudsen proposed a method of attacking block ciphers t hat used the higher order differential, and in FSE4: Jakobsen and Knudsen a pplied it to a cipher proposed by Nyberg and Knudsen. Their approach, howev er, requires large complexity of running time. In this paper, we improve th is attack and show that our improved algorithm requires much fewer chosen t exts and much less complexity than those of previous works.