A HIGHLY NON-LINEAR AND ROBUST DYNAMIC S-BOX FORCRYPTOGRAPHIC APPLICATIONS

Abstract

Substitution Boxes (S-Boxes) are used to introduce confusion in Data Encryption Standard (DES). Confusion renders the relationship as dynamic as possible between the plaintext and the text of the cypher. DES uses eight S-boxes which are static in nature that is the contents of the S-box are not changing. Each of these 8 S-boxes receives an input of 6 bits and generates a 4 bit output. The S-box contents are not dependent on the plain-text or the key. In this paper, a novel, dynamic S-box for DES is proposed. The Dynamic S-box is keydependent. The proposed system produces 8 Dynamic S-boxes each receive 6 bit input and produce 4 bit output. The two different methods are analysed and this paper compares the non-linearity,delta uniformity and Robustness to Differential Cryptanalysis of the two different DES S-boxes. The proposed system is implemented and analysed. The analysis result shows that the dynamic S-box is highly non-linear,Robust to Differential Cryptanalysis and highly secure when compared to static DES S-box.