Match Box Meet-in-the-Middle Attack Against KATAN

Recent years have seen considerable interest in lightweight cryptography. One particular consequence is a renewed study of meet-inthe-middle attacks, which aim to exploit the relatively simple key schedules often encountered in lightweight ciphers. In this paper we propose a new technique to extend the number of rounds covered by a meet-inthe-middle attack, called a match box. Furthermore, we demonstrate the use of this technique on the lightweight cipher KATAN, and obtain the best attack to date on all versions of KATAN. Specifically, we are able to attack 153 of the 254 rounds of KATAN32 with low data requirements, improving on the previous best attack on 115 rounds which requires the entire codebook.