Secret Key Cryptography Using Graphics Cards

One frequently cited reason for the lack of wide deployment of cryptographic protocols is the (perceived) poor performance of the algorithms they employ and their impact on the rest of the system. Although high-performance dedicated cryptographic accelerator cards have been commercially available for some time, market penetration remains low. We take a different approach, seeking to exploit {\it existing system resources,} such as Graphics Processing Units (GPUs) to accelerate cryptographic processing. We exploit the ability for GPUs to simultaneously process large quantities of pixels to offload cryptographic processing from the main processor. We demonstrate the use of GPUs for stream ciphers, which can achieve 75\% the performance of a fast CPU. We also investigate the use of GPUs for block ciphers, discuss operations that make certain ciphers unsuitable for use with a GPU, and compare the performance of an OpenGL-based implementation of AES with implementations utilizing general CPUs. In addition to offloading system resources, the ability to perform encryption and decryption within the GPU has potential applications in image processing by limiting exposure of the plaintext to within the GPU.