适合SMS4算法硬件实现的S盒构造新方法

基于有限域求逆实现s盒的方法存在求逆运算复杂、硬件实现难的问题.为此,通过引入新的复合域,将GF(2~8)域上的求逆运算转化成GF(((2~2)~2)~2)复合域上的求逆运算,提出了一种基于复合域求逆的低电路面积开销的s盒构造方法.该方法通过采用复合域计算、优化运算顺序和复用公因子等手段减小S盒硬件实现的电路面积.实验表明,在0.18μm和0.35μm CMOS工艺下,采用基于复合域求逆构造的S盒与采用查找表方法构造的S盒相比,电路面积可减少34%～68%.此外,在相同的工艺和吞吐率下,与原始的算法相比,采用提出的S盒的SMS4算法硬件资源消耗大大减少,适用于对芯片面积严格限制的场合.

A new algorithm of S-box for hardware implementation of SMS4

In order to solve the problem of the implementation algorithm of S-box based on the inversion transformation over Galois field,methods such as composite field computation,altering calculation order and sharing factors have been used to optimize operations.A low hardware overhead implementation algorithm of S-box based on the inversion transformation approach from GF(2~8)to GF(2~2)was presented.Compared with the implementations based on look-up table method,this algorithm can reduce circuit area by 34%～68%using 0.18μm and 0.35μm CMOS technology.This design method can make SMS4 algorithm more suitable for area-critical devices.