| Wireless networks, without doubt, have become one the most popular technologies nowadays. These wireless networks are now being used almost everywhere in the world, from commercial applications, such as a School/Office WLAN (Wireless Local Area Network) giving every student/employee wireless access to Internet anywhere in the campus, to military applications, such as a Wireless Sensor Network implemented in the battlefield to monitor enemy's army activities. In most cases, there are always requirements for protecting the confidentiality and privacy of data transmitting on the air. This task, however, is not trivial. Implementing security services on traditional Internet, where end points are powerful computers and servers, has not been completely successful. The fact that data is being transmitted over the air adds more complications to the task. In this dissertation, we are concerned about some of the most challenging problems in wireless network security. First, we consider protecting wireless ad hoc networks from Wormhole attacks, which are difficult to defend against because the attacker neither needs to break authentication framework nor needs to steal encryption keys of the legitimate nodes. Next, we study the Stealthy attack in wireless sensor networks, in which the attacker tries to fool users into accepting wrong data. The privacy problem in wireless sensor networks is also considered. Finally, we study and propose solutions for defending against a simple but effective denial of service attacks on WLAN. For each problem in this dissertation, we carefully examine the attack model, suggest novel solutions and verify them by a combination of experiments, simulations and/or mathematical analysis.;Our contribution is not only limited to the solution of each problem, but we also show that complex problems can often be solved by applying simple ideas, which turn out to be very efficient and practical to apply in reality. |
