AES S盒的分析及改进方案设计

研究了AES S盒的构造原理和主要代数性质，指出了AES S盒的仿射变换对周期为4，迭代输出周期不大于88，严格雪崩准则距离为432，代数表达式只有9项等。基于这些不足提出了构造S盒的改进方案。改进S盒的仿射变换对周期为16，迭代输出周期为256，而且S盒和逆S盒代数表达式项数均达到254项。将改进S盒与AES的S盒在平衡性、严格雪崩准则、非线性度、抗代数攻击阻力等10种代数性质上进行比较，实验结果表明改进S盒具有更好的性质。

Analysis of AES S-box and design of its improved method

This paper studies the construction principle and main algebraic properties of AES S-box,points out the S-box has these characteristics that periods of affine transformed pair is 4,periods of iterative-output is less than 88,strict avalanche criterion distance is 432,the algebraic expression has only 9 items and so on.Based on that,an improved S-box has been constructed.Periods of affine transformed pair is 16 and periods of iterative-output is 256 and both the algebraic expression of S-box and InvS-box have 254 items in the improved S-box.The improved S-box has been compared with AES S-box in 10 algebraic properties,such as balanceness,strict avalanche criterion,non-linear degree,resistance against the XSL attack etc.The experimental results suggest that the improved S-box has better characteristics.