DES bitslice S-boxes

[Matthew Kwan]

I've been a bit out of touch with the subject for a while, so could
someone please bring me up to speed in the state of the art of DES
bitslice. In particular, what are the best gate counts for the S-boxes?

About a year ago I produced S-boxes with the following counts

        S-box   S1   S2   S3   S4   S5   S6   S7   S8
        Gates   95   84   89   77   96   87   86   88

(You can download them from http://www.cs.mu.oz.au/~mkwan/bitslice)

However, I was recently told that these have now been beaten by a
significant margin. I thought about it for a while, and came up with
some ideas that should improve the count, but I'd like to know what
I'm aiming for.

Any improvements I make will also be made freely available, so you
have an incentive to help me ;-)


mkwan