The saturation attack on a novel block cipher CLEFIA

which was proposed in FSE 2007

was reevaluated.The flaws in Shirai et al’s 8 round distinguishers were pointed out and corrected.In order to reduce the number of guessed subkeys

the attack utilized the movement of the whitening key to combine it with subkey

and explored a di-vide-and-conquer strategy.The partial sum technique was adopted to reduce the time complexity.As a result

the satura-tion attack can be extended from 10 round variant without key whitenings to 11 round CLEFIA-128/192/256

and is ap-plicable to 12 round CLEFIA-192/256 and 13 round CLEFIA-256.