Impossible Differential Cryptanalysis of Lightweight Block Cipher WARP

Abstract

WARP is a lightweight block cipher with 128-bit key size and block size, which can be used as a lightweight replacement of AES-128 without changing the mode of operation. In this paper, we proposed an automatic search algorithm for impossible differentials of WARP with SAT method and searched for impossible differentials of WARP up to 21 rounds. Using one impossible differential of 21-round WARP, we present an impossible differential cryptanalysis of 33-round WARP by appending six rounds before and after the distinguisher, which covers the same round as the best zero-correlation linear attack on WARP in the single-key setting.