[RC5] oddball DES vs. CPU speeds

Svend Olaf Mikkelsen svolaf at inet.uni2.dk
Fri Jan 16 01:35:15 EST 1998

On Wed, 14 Jan 1998 23:59:03 +0100, Remi Guyomarch
<rguyom at mail.dotcom.fr> wrote:

>Yes, with the current core Pentiums are faster than PPro. A 200 MHz
>Pentium cracks ~980 kkeys/s when a 200 Mhz PPro cracks ~850 kkeys/s
>(test under NT4).
>We took the BrydDES core as-is, and it was optimized for the Pentium
>(perhaps simply  because its author (Svend Olaf Mikkelsen) had access to
>only a Pentium and not a Pentium Pro...).
>If someone is foolish enough to convert the BrydDES source code () from
>MASM to AT&T by hand (71 KB), or smart enough to design a converter, I
>will be happy to try something ;-)

In my key search routine a key is tested in about 400 instructions.
Out of this the code for round 3 to 11 takes 297 instructions. The
code for these rounds is simple, easy to change and easy to test. It
is basically 33 instructions (could be fewer) repeated 9 times.

If the code should be optimized for different x86 processors, I guess
this is the only code I would touch.

If you want I could make a version which call external procedures for
round 3 to 11 and convert it to aout format.

While I am here:

The bswap instruction which is illegal on 386 was removed in the
January 10 library version, but I understand that one would not change
library version just at the moment for release.

And then the Windows 95 speed puzzles me. On my 120 MHz Pentium the
client runs at above 600 K key/second in Windows NT, but only at about
550 K keys/second in Windows 95. I don't know the current plans, but I
could consider looking into this. One possible solution could be to
make a version, which has a slightly lower maximum speed, but runs in
less memory and might be less sensitive to conditions in Windows 95.

Svend Olaf

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