International Association for Cryptologic Research

International Association
for Cryptologic Research


Bing Sun,Ruilin Li


Impossible Differential Cryptanalysis of CLEFIA
Bing Sun,Ruilin Li Mian Wang Ping Li Chao Li
This paper mainly discussed the impossible differerential crypt- analysis on CLEFIA which was proposed in FSE2007. New 9-round impossible differentials which are difrererent from the previous ones are discovered. Then these differerences are applied to the attack of reduced-CLEFIA. For 128-bit case, it is possible to apply an impossible differen-tial attack to 12-round CLEFIA which requires 2^110.93 chosen plaintexts and the time complexity is 2^111. For 192/256-bit cases, it is possible to apply impossible differential attack to 13-round CLEFIA and the chosen plaintexts and time complexity are 2^111.72 and 2^158 respectively. For 256-bit cases, it needs 2^112.3 chosen plaintexts and no more than 2^199 encryptions to attack 14-round CLEFIA and 2^113 chosen plaintexts to attack 15-round 256-bit CLEFIA with the time complexity less than 2^248 encryptions.


Ping Li (1)
Chao Li (1)
Mian Wang (1)