Provable security for an RC6-like structure and a MISTY-FO-like structure against differential cryptanalysis

Abstract

In this paper we introduce two new block cipher structures, named RC6-like structure and MISTY-FO-like structure, and show that these structures are provably resistant against differential attack. The main results of this paper are that the 5-round differential probabilities of these structures are upperbounded by p4 + 2p5 and p4, respectively, if the maximum differential probability of a round function is p. We also discuss a provable security for the RC6-like structure against LC. Our results are attained under the assumption that all of components in our proposed structures are bijective. © Springer-Verlag Berlin Heidelberg 2006.