Demand in the consumer market for graphics hardware that accelerates rendering of 3D images has resulted in commodity devices ca- pable of astonishing levels of performance. These results were achieved by specifically tailoring the hardware for the target domain. As graphics accelerators become increasingly programmable this performance makes them an attractive target for other domains. Specifically, they have mo- tivated the transformation of costly algorithms from a general purpose computational model into a form that executes on said graphics hard- ware. We investigate the implementation and performance of modular exponentiation using a graphics accelerator, with the view of using it to execute operations required in the RSA public key cryptosystem.