Kasumi算法FI函数的差分上界分析

Differential Upper Bound on the FI Function of Kasumi Algorithm

差分分析是目前攻击分组密码十分有效的方法之一。证明了FI函数的平均差分概率上界值,重点分析了FI函数在各种变形下的平均差分概率上界。结果表明:对于FI函数这种结构,采用奇数维S盒可使得平均差分概率上界达到22-n。

Differential cryptanalysis is an efficient method to attack block ciphers.The purpose of this paper is to give an upper bound to the average differential probability of FI functions.Moreover,it is showed that there exist functions such that the average differential probabilities are less than or equal to 22-n.