Enhancing Security and Speed of RC4

Abstract

Wireless communication security is a critical factor for secure communication among large scale of wireless networks. A limited resource constraint, such as power and memory size presents a significant challenge to implement existing cryptographic algorithms. One of the most important symmetric cryptographic algorithms is Rivest Cipher 4 (RC4) stream cipherthatis utilized in many real-time security applications. However, the RC4 cipher shows some weaknesses, including a correlation problem between the public known outputs of the internal state. In this paper, we propose RC4 stream cipher with a random initial state (RRC4) to solve the weak keys problem of the RC4 using a random initialization of internal state S. We also propose RC4 stream cipher with two state tables (RC4-2S) to solve the correlation problem between the public known outputs of the internal state using permutation between state1 (S1) and state 2 (S2) while requiring less time than RC4. Finally, we propose RC4 stream cipher with two state tables togenerate four keys (RC4-2S+) in each cycle which further enhances randomness overRC4-2S and RRC4.