A WEP post-processing algorithm for a Robust 802.11 WLAN implementation

Abstract

Wired Equivalent Privacy (WEP) protocol used within the IEEE 802.11 standard has “major security flaws” thus wireless local area networks (WLANs) using the protocol are vulnerable to attacks. In this paper, we propose a scrambling algorithm that reduces the security vulnerabilities of the WEP. The algorithm randomizes the data and prevents access from unauthorized users by adding some standard randomness to it. This random characteristic is a function of the private attribute shared between transmitter and receiver only. In this approach the randomness is achieved by RC4 algorithm, and the distribution of the randomness is provided with different algorithms to increase the complexity of rectifying the encrypted data and optimize utilization of the randomness. The algorithm is developed with a consideration for the least computational requirements to achieve both power and cost efficiency. The proposed software solution takes the WEP output as input and the original WEP implementation is not touched, thus it is an easy patch for the deployed systems.

Introduction

Internet enabled wireless devices continue to proliferate and are expected to surpass traditional wired Internet clients in the near future. The use of wireless networking is rapidly rising with an ever-increasing need for businesses to cut costs and provide mobility to workers. Wireless technology has spread to devices from small-embedded systems to large general purpose PCs. This is due to cheaper prices, faster speeds and also due to the need for greater mobility. However, data security and privacy remain major concerns in the current generation of wireless networks. Wireless network security is very essential as it is not bound to any region. Any unauthorized person can read, modify or use the private data being transmitted over a network. As wireless platforms mature, grow in popularity, and store valuable information, hackers are stepping up their attacks on wireless targets. Thus, wireless security has become an important area of research and development. As in the wired world, wireless security boils down to protecting information and preventing unauthorized system access. However, it is challenging to implement security in small-footprint devices with low processing power and small memory capacities. IEEE 802.11 Wireless Fidelity (Wi-Fi) standard based systems are ubiquitously available. The standard refers to a family of specifications developed for wireless local area network (LAN) technology [1]. It specifies an over-the-air interface between a wireless client and a base station or between two wireless clients. The need for the 802.11 standard came due to the emergence of various proprietary wireless systems, which were incapable of interoperation. The standard has become popular due to its high data rate and its fast and easy encryption techniques. It is modeled on the ISO’s OSI Model but the standard is only concerned with the physical layer and the lower part of the data link layer (i.e., the Medium Access Control (MAC) sub-layer [2], [3]). The 802.11 architecture uses fixed network access points (APs) with which mobile nodes can communicate. These network APs are sometimes connected to landlines to widen the LAN’s capability by bridging wireless nodes to other wired nodes. The Wi-Fi standard is designed to provide a wireless LAN with a level of security and privacy comparable to what is usually expected of a wired LAN, using Wired Equivalent Privacy (WEP) security protocol [1]. WEP is a popular wireless secure communications stream cipher protocol. It allows users to communicate with other users sharing the public key over a network. It provides authentication and encrypted communications over unsecured channels. However, several studies have demonstrated that WEP is vulnerable to various attacks and it fails to achieve its security goals [4], [5], [6], [13], [15], [18]. The serious security flaws that have been discovered in the protocol stem from misapplication of the cryptographic primitives. The so-called WEP attacks appear in the form of intercepting and modifying the transmissions, and gaining access to restricted networks. In this paper, we propose an algorithm to patch the WEP protocol against these attacks. The developed algorithm requires a minimal solution for the various attacks in the WEP protocol. It offers guidelines to develop a practical and a viable infrastructure for robust 802.11 implementation. The proposed solution can be easily deployed within the WEP-capable equipments. This can be done by upgrading the software in the existing systems.

The rest of the paper is organized as follows: An overview of WEP is given in Section 2; the proposed scrambling algorithm is introduced in Section 3; analysis of the proposed algorithm is presented in Section 4; the paper ends with some conclusions and directions for future work in Section 5.

Table 1 summarizes the nomenclature that is used in the remainder of the paper.