RC4X: A New Enhancement over RC4 Encryption Security

Abstract

The RC4 stream cipher has known security weaknesses due to its weak keystream distribution and biased key scheduling. In this article, an extended RC4X is proposed to enhance the security of the original RC4 stream cipher by combining sophisticated mixing methods into its Key Scheduling Algorithm (KSA-X) and Pseudo-Random Generation Algorithm (PRGA-X) process. The proposed KSA-X uses two full-shuffle operations to eliminate predictable key-byte relationships: a first RC4-style permutation and a nonlinear mixing function that performs bitwise shifts and XOR operations. The internal state becomes more unpredictable through an additional permutation phase, which diffuses the state elements and increases the randomness. The PRGA-X update mechanism performs state-value rotations to reduce linear dependencies and minimize distribution-related weaknesses in the generated keystream. The experimental results show that RC4X produces keystreams with improved higher-order correlation properties, enhanced resistance to key-recovery attacks, and fast operation and efficient memory usage. The study proves the fact that RC4X is a lightweight, secure substitute of RC4, which is utilized where maximum efficiency and security are needed and minimum resources are at hand. The experimental findings indicate that RC4X provides security against many known security weaknesses and offers equivalent performance as the traditional stream ciphers. The distance-equalities statistical test will assist us in determining structural flaws in algorithmic keystreams created by similar algorithms such as RC4. This test has been done to identify the statistical bias in RC4. The largest RC4 bias is subsequently fixed by RC4X. Precisely, the most critical RC4 deviation (Event-2 bias) was narrowed down to -11.59X -0.14X in RC4X.