Improved meet‐in‐the‐middle attacks on Crypton and mCrypton
Rongjia Li, Chenhui Jin · IET Information Security · 2016
This study presents several meet‐in‐the‐middle attacks on reduced‐round Crypton and mCrypton block ciphers. Using the generalised δ ‐set, the authors construct 5‐round distinguishers on Crypton and mCrypton. Based on these distinguishers, the authors propose meet‐in‐the‐middle attacks on 8‐round Crypton and mCrypton‐96/128. The attack on Crypton needs 2 121 chosen plaintexts, 2 132 encryptions and 2 130 128‐bit blocks; the attacks on mCrypton need 2 61 chosen plaintexts, 2 80 encryptions and 2 78 64‐bit blocks. Furthermore, the attack can be extended to 9 rounds for mCrypton‐128 with complexities of 2 61 chosen plaintexts, 2 112 encryptions and 2 82 64‐bit blocks.