Differential Cryptanalysis of K-Cipher

Abstract

K-Cipher is an ultra low latency block cipher with variable-length parameters designed by Intel Labs. In this work, we analyze the security of K-Cipher and propose a differential cryptanalysis attack with the complexity of 2(29:7) for a variant of K-Cipher with state size n = 24 bits state and block size m = 8 bits. Our attack recovers the secret key and secret randomizer values with a total length of 240 bits in similar to 30 minutes on a standard desktop machine. We show that it is possible to extend the same attack for an arbitrary set of parameters.