خوارزميـــات تأمين الشـبكات المحـلية اللاسـلكيـة , Security Algorithms for Wireless Local Area Networks

                             1.1 Motivation and thesis organization

This thesis begins with an overview covering the basic structure of wireless LAN, basic infrastructure components, its architecture and how it operates. In chapter two, the different IEEE wireless LAN standards and different frequency bandwidths are presented .

Then in chapter three, the wireless LAN vulnerabilities are discussed, various kinds of attacks had been studied, then the access security and authentication and security standard methodologies had been described. The wired equivalent privacy protocol security problems and classical temporal key integrity protocol are discussed in depth within chapter four.

In chapter five, the process of classical temporal key integrity protocol details are covered as well as the message integrity control. Then the two proposals of the modified temporal key integrity protocol are presented and their requirements, the software platform to implement the TKIP algorithms is described. To validate and compare between the randomness properties of the classical and proposed modified TKIP algorithms, the standard set of statistical tests is presented. As a simulation of the implemented classical and proposed modified algorithms, two examples for two plaintext paragraphs are encrypted and tested according to the standard statistical tests. Then results of 50 sample paragraphs have been tabulated for the two proposed algorithms. A comparison between the classical and proposed modified algorithm in the randomness properties is shown to provide the improvement done within the encryption performance. At the end of the chapter, the key management policy is discussed.

Afterwards, in chapter six the conclusion of the research is shown in addition to the proposed future research areas. After the last chapter, there are two appendices for the distributions and an algorithm implementation C code. The used references are listed finally.

There are various ways to build a wireless LAN; different implementations are carried out through different combinations of methods, technologies and architectures. There are evolving standards to go with the market and users requirements “Speeds, throughput, security, etc…”

The WLAN security can be achieved through different algorithms and approaches. Each one has its benefits and shortcomings. In this thesis, an effort is done to arrive at a good one taking care of the various conditions.

The market for wireless LANs seems to be evolving in a similar fashion to the networking industry as a whole, starting with the early adopters using whatever technology was available. The market has moved into a rapid growth stage, for which popular standards are providing the catalyst. The big difference between the networking market as a whole and the wireless LAN market is the rate of growth [1].

Spread spectrum wireless networks, like many technologies, came of age under the guidance of the military. The military needed a simple, easily implemented, and secure method of exchanging data in a combat environment.

As the cost of wireless technology declined and the quality increased, it became cost effective for enterprise companies to integrate wireless segments into their network. Wireless technology offered a relatively inexpensive way for corporate campuses to connect buildings to one another without laying copper or fiber cabling. Today, the cost of wireless technology is such that most businesses can afford to implement wireless segments on their network, if not convert completely to a wireless network, saving the company time and money while allowing the flexibility of roaming.

Households are also benefiting from the low cost and subsequent availability of wireless LAN hardware. Many people are now creating cost-effective wireless networks that take advantage of the convenience of mobility and creating home offices or wireless gaming stations.

As wireless LAN technology improves, the cost of manufacturing (and thus purchasing and implementing) the hardware continues to fall, and the number of installed wireless LANs continues to increase.

The standards that govern wireless LAN operation will increasingly stress interoperability and compatibility. As the number of users grows, lack of compatibility may render a network useless, and the lack of interoperability may interfere with the proper operation of other networks [2].

1.2 Applications of Wireless LANs

When computers were first built, only large universities and corporations could afford them. Wireless LANs have taken a similar path, first used by large enterprises, and now available to all customers at affordable prices. As a technology, wireless LANs have enjoyed a very fast adoption rate due to the many advantages they offer to a variety of situations [3].