The Meet-in-the-middle Attacks on Zodiac

Zodiac is a block cipher designed by a group of Korean experts. This paper studies the security of Zodiac against the meet-in-the-middle attack for the first time. Some new 9-round and 10-round distinguishers of Zodiac are found, and based on which some meet-in-the-middle attacks are made on 15-round and the full 16-round Zodiac. The results show that the full Zodiac-128/192/256 are not immune to the meet-in-the-middle attack.