After a WPA/WPA 2 Handshake Capture has been saved to a drive cracking it with current computers can be challenging. To speed this process up the GPU in some video cards can be utilized. This can speed things up drastically when doing a brute force crack on a WPA data capture. You will need to know the video card you are currently using and Google it to see if it is compatible.
Most often aircrack-ng is used to show how to crack a WPA capture with a dictionary. In this example a tool called oclHashCat will be used in order to utilize a video cards GPU. A dictionary file and the data capture are still needed only we will be using the video cards GPU to speed up the process. Always check to see if your card is compatible and the correct drivers are loaded.
Nvidia and AMD/ATI Video cards use two separate hashcat names
The two main versions of HashCat are:
oclHashCat for AMD/ATI graphics cards
cudaHashCat for Nvidia graphics cards
You can download both from here http://hashcat.net/files/oclHashcat-plus-0.14.7z
Extract it with 7z x oclHashcat-plus-0.14.7z (Don’t use 7x e as it will not preserve the directory structure.)
To use hashcat the .cap file needs to be converted to ahccap file to do this use air-crack-ng
Run hashcat against your new capture file using the correct version.
cudaHashcat-plus32.bin -m 2500