I would recommend you to use Kali Linux OS because this OS has built-in software's such as Aircrack-ng (set of tools for auditing wireless networks) which helps in cracking WEP and WPA-PSK keys. To crack a network you also need to have the right kind of Wi-Fi adapter in your computer, one that supports packet injection. You need to be comfortable with the command line (running things using CMD) and have a lot of patience. Your Wi-Fi adapter and Aircrack have to gather a lot of data to get anywhere close to de-crypting the passkey on the network you're targeting. It could take a while. Ng suite is the best collection of tools to do WiFi pentesting. These tools are: Airmon-ng Aircrack-ng Airodump-ng For cracking aircrack-ng is being used for a long time. Latest version is Aircrack-ng 1.2 RC 2 and can be downloaded for windows or Linux from www.aircrack-ng.org They come preloaded in Kali, backtrack. Also, they are available for OpenWRT platform.