A differential attack on the CIKS-1 block cipher

A. and N. Moldovyan (see J. Cryptology, vol.15, p.61-72, 2002) introduced a cipher, called CIKS-1, with security based mainly on data-dependent permutations (DDPs). The goal of the cipher was to exploit the speed and simplicity of DDPs to create a fast hardware-oriented block cipher. In the original paper, the authors claimed that the cipher is immune to differential cryptanalysis. This paper investigates the propagation of differentials through the cipher. An attack is then presented to reveal the last subkey of the cipher with a data complexity better than previously claimed.