## Cryptology ePrint Archive: Report 2020/1598

MILP Based Differential Attack on Round Reduced WARP

Abstract: WARP is proposed by S. Banik et al. in SAC 2020. It is a 128-bit lightweight block cipher with 128-bit key. WARP is based on 32-nibble type-2 Generalised Feistel Network (GFN). It uses permutation over nibbles designed to optimize the security and efficiency. Designers have provided a lower bound for the number of differentially active S-boxes but detailed differential characteristics are not provided. In this paper, we discuss MILP based search technique and present differential characteristics for 18-round and 19-round WARP with probability of $2^{-122}$ and $2^{-132}$ respectively. To the best of our knowledge, these detailed differential characteristics for WARP are presented for the first time.

Category / Keywords: secret-key cryptography / Lightweight Cryptography, Block Cipher, Differential Cryptanalysis, MILP