Fast Implementations of AES Candidates

Of the five AES finalists four—MARS, RC6, Rijndael, Twofish— have not only (expected) good security but also exceptional performance on the PC platforms, especially on those featuring the Pentium Pro, the NIST AES analysis platform. In the current paper we present new performance numbers of the mentioned four ciphers resulting from our carefully optimized assemblylanguage implementations on the Pentium II, the successor of the Pentium Pro. All our implementations follow well-defined API and timing conventions and sensible guidelines, like no using of self-modifying code and key-specific static data — i.e., tricks that speed up the implementation but at the same time restrict the field of application. Our implementations are up to 26% percent faster than previous implementations. Our work also shows how a simple change (inclusion of the MMX technology) in the analysis platform can influence the relative encryption speed of different ciphers. To enable everyone to compare their implementations to ours, we also fully specify our procedures used to obtain the speed numbers.