Improving DES coprocessor throughput for short operations

Over the last several years, our research team built a commercially-offered secure coprocessor that, besides other features, offers high-speed DES: over 20 megabytes/second. However, it obtains these speeds only on operations with large data lengths. For DES operations on short data (e.g., 8-80 bytes), our commercial offering was benchmarked at less than 2 kilobytes/second. The programmability of our device enabled us to investigate this issue, identify and address a series of bottlenecks that were not initially apparent, and ultimately bring our short-DES performance close to 3 megabytes/second. This paper reports the results of this real-world systems exercise in hardware cryptographic acceleration--and demonstrates the importance of, when designing specialty hardware, not overlooking the software aspects governing how a device can be used.