Cryptanalysis of TWIS block cipher

Abstract

TWIS is a 128-bit lightweight block cipher that is proposed by Ojha et al. In this work, we analyze the security of the cipher against differential and impossible differential attacks. For the differential case, we mount a full-round attack on TWIS and recover 12 bits of the 32-bit final subkey with 2 21 complexity. For the impossible differential, we present a distinguisher which can be extended to a key recovery attack. Also, we showed that the security of the cipher is only 54 bits instead of claimed 128 bits. Moreover, we introduce some observations that compromise the security of the cipher. © 2012 Springer-Verlag.