对CLEFIA算法的饱和度分析

Saturation cryptanalysis of CLEFIA

评估了2007年提出的分组加密算法CLEFIA抗饱和度分析的强度。指出并改正了CLEFIA的设计者Shirai等人提出的8圈区分器的错误。将白化密钥和子密钥结合,并利用分别征服策略减少需要猜测的密钥个数,采用"部分和"技术以降低时间复杂度。从而,将对10圈CLEFIA的饱和度攻击扩展到11圈的CLEFIA-128/192/256。此外,该攻击还可应用到12圈的CLEFIA-192/256和13圈的CLEFIA-256。

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 saturation attack can be extended from 10 round variant without key whitenings to 11 round CLEFIA-128/192/256, and is applicable to 12 round CLEFIA-192/256 and 13 round CLEFIA-256.