DFC Update

This document reports an update of DFC. We answer to a question about the rationale for the CP Confusion Permutation. We give new implementation results for DFC. In particular we present an impressively fast implementation which takes 323 cycles on Compaq's 21164 Alpha microprocessor. On the new 21264 we expect to reach software encryption rates over 500 Mbps. We also discuss making DFC scalable to allow the block size or the number of rounds, in the encryption or key schedule, to be varied. Finally, we describe how DFC may be subject to slight change in its key schedule in order to fix a minor drawback noticed by Coppersmith.