Dynamic extended DES

Abstract

The original S-boxes of DES are important algorithms to resist differential attack. Furthermore, Yeh and Hsu proposed the extended DES, which developed eight more new S-boxes with the same cryptographic properties as original S-boxes in DES. These 16 S-boxes are used to construct the extended DES, which double the block cipher and key size. As a result, a time complexity of differential cryptanalysis of the extended DES is 2¹¹⁰. In this paper we propose an intricate extended DES that includes permutation on S-boxes. By keeping the permutation information in secret, the new version of extended DES is stronger to defeat differential and linear attacks 20922789888000 times.

Keywords:

• S-Boxes
• DES
• block cipher
• differential attack
• linear attack