New Approach for Modifying DES Algorithm Using 4-States Multi-keys

Abstract

Within the last decade, there has been a vast increase in the accumulationand communication of digital computer data in both the private and public sectors.Much of this information has a significant value, either directly or indirectly, whichrequires protection. One of the most important protection methods is inventing anddeveloping different encryption algorithms. The algorithms uniquely define themathematical steps required to transform data into a cryptographic cipher and alsoto transform the cipher back to the original form.This paper introduces a new method to enhance the performance of theData Encryption Standard (DES) algorithm. This is done by replacing thepredefined XOR operation applied during the 16 round of the standard algorithmby a new operation depends on using two keys, each key consists of a combinationof 4 states (0, 1, 2, 3) instead of the ordinary 2 state key (0, 1). This replacementadds a new level of protection strength and more robustness to breaking methods.