Algebraic Expression for AES S-box and InvS-box
Liu Lian-hao · Jisuanji gongcheng · 2006
This paper presents an algebraic method that the component of the field element can be expressed by a simple polynomial with the element itself as the variable over GF(28 ) . The algebraic expressions of S-box and InvS-box can be resolved and the reasons why S-box has only 9 items but InvS-box has 255 items are explained with this method. In addition it proposes a quick power algorithm for polynomial over finite field. The experimental results indicate that the algorithm is better than direct multiplication.