Analysis of RC4 and proposal of additional layers for better security margin

Abstract

In this paper, the RC4 Key Scheduling Algorithm (KSA) is theoretically studied to reveal non-uniformity in the expected number of times each value of the permutation is touched by the indices i, j. Based on our analysis and the results available in the literature regarding the existing weaknesses of RC4, few additional layers over the RC4 KSA and RC4 Pseudo-Random Generation Algorithm (PRGA) are proposed. Analysis of the modified cipher (we call it RC4+) shows that this new strategy avoids existing weaknesses of RC4. © 2008 Springer Berlin Heidelberg.