Brute force password cracking has been around for a while but in the last few years a new way to use your brand new graphic card has emerged which brings high performance attacks against passwords much cheaper and easier.

This is because the “brain” of those graphical card, The Graphical Processing Unit or GPU, is designed to handle mathematical and repetitive tasks very efficiently.

There is a very good article about this topic on the ERRATA SECURITY blog with some interesting facts:

– Although GPU are now found in most electronic devices (i.e.: phones), dedicated PC cards are obviously better

– Radeon is better than GeForce

– Although you can use more than one GPU, the benefits are not exponential and most people only need 1 or 2 GPU.

– This is because past 8 Characters, a password become near impossible to brute force. It would take too long, regardless of the number of GPU you use!

– Some people actually slow the speed of the computer memory to reduce voltage and thus heat. All that matters is the GPU!

– What you would use a GPU against:

• Bitcoin hashes match calculation (Bitcoin is a digital currency)
• WPA Passwords, as you cannot really use Rainbow tables, brute force can be useful! in fact this is true for any “salted’ passwords.
• Protected documents: ZIP, Office, etc

Some of the software you need if you want to experiment yourself can be found on the Golubev website.

Update 28/06:
It looks like you can even now have external powerful GPU cards for your notebook, and it is a Radeon!
SONY EXTERNAL GPU DOCK