RC4 Code Achieves 319 MB/s On AMD64 Opteron

Posted by timothy on Monday November 1, 2004 @11:22PM from the even-more-thingy dept.

Marc Bevand writes "This recent paper is about optimizing RC4 for AMD64 processors. A working implementation is provided. Its encryption/decryption throughput reaches 319 MB/s on a single AMD Opteron x44 processor running at 1.8 GHz. This makes it, as of today, the world's fastest RC4 symmetric cipher implementation for general purpose CPUs. As the author of this work, I would like to point out that many CPU-hungry applications have not been optimized for AMD64 yet. In other words: such speedups can be expected in other areas." An anonymous reader adds some figures for the old implementation: "Opteron 244 1.8 GHz (32-bit) 163 MB/s; Opteron 244 1.8 GHz (64-bit) 135 MB/s."

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Re:Does this change anything for rc5? by RupW · 2004-11-02 00:44 · Score: 5, Interesting

Will the optimized AMD64 rc4 code provide any boost to those crunching rc5 on an AMD64?

No, they're entirely different. For a start, RC4 is a stream cipher whereas RC5 is a block cipher. They just share the same inventor, hence the names.

AFAICR, the RC5 effort uses the register width to try and crack many keys in one go anyway - a different approach to this, which is using the register width to generate more of a single stream in one go.