Meet-in-the-Middle Attack on Reduced Versions of the Camellia Block Cipher

International audienceThe Camellia block cipher has a 128-bit block length and a user key of 128, 192 or 256 bits long, which employs a total of 18 rounds for a 128-bit key and 24 rounds for a 192 or 256-bit key. It is a Japanese CRYPTREC-recommended e-government cipher, a European NESSIE selected cipher, and an ISO international standard. In this paper, we describe a few 5 and 6-round properties of Camellia and finally use them to give meet-in-the-middle attacks on 10-round Camellia under 128 key bits, 11-round Camellia under 192 key bits and 12-round Camellia under 256 key bits, all of which include the FL/FL −1 functions but do not include whitening operations