[RC5] keyrate stabilizing?

Test Man mr_nobby at yahoo.com
Mon Oct 22 00:34:07 EDT 2001


Is it really true that some CPUs do not have rotate
instructions? I mean, a rotate is effectively a shift
register - which is one of the fundamental blocks of
digital electronics. Even the Sinclair ZX80 had one!
And rotate/shift instructions are a very quick way of
multiplying or dividing by powers of 2.

Sorry if I'm out of place on this one or if it has
already been covered, but I've just joined the list.

--- Zorba the Hutt <zorbathut at uswest.net> wrote:
> 
> Yeah, but how much CPU does SSL/SSH really take up?
> I used SSH a little on
> my P166, and I didn't exactly have to shut down all
> my programs. Not only
> that, but with the ever-tightening encryption laws,
> perhaps focusing on
> making the (already-fast) encryption even *faster*
> isn't a good use of their
> time.
> 
> The people who use CPU power are, for the vast
> majority, gamers,
> programmers, artists, and people who need lots of
> servers. The only one of
> those who cares about rotating bits is the last, and
> only if they're doing
> encryption.
> 
> It just plain isn't worth it.
> 
> -Zorba
> 
> ----- Original Message -----
> From: "Christopher Hicks" <chicks at chicks.net>
> To: <rc5 at lists.distributed.net>
> Sent: Saturday, October 20, 2001 10:40 AM
> Subject: Re: [RC5] keyrate stabilizing?
> 
> 
> > On Fri, 19 Oct 2001, Dan Sugalski wrote:
> >
> > > While rotates are useful in this case, and a few
> other isolated
> > > places, this is such an edge case that it's just
> not worth the silicon
> > > that it'd take to implement a rotate
> instruction. Not having one
> > > simplifies the ALU a bunch, and that speeds up
> the core and leaves
> > > more room for other things.  Even if a CPU fakes
> it, like the newest
> > > intel and AMD chips likely do, you still get a
> win. (Heck, if all
> > > tossing rotate out got you was another line in
> your L1 cache it'd be
> > > worth it...)
> >
> > In this day and age I would think that working
> well on encryption would be
> > more of a priority for CPU designers.  It hardly
> seems like an edge
> > application to someone that uses ssl and ssh on a
> daily basis.
> >
> > --
> > </chris>
> >
> > Neither sweat, nor blood, nor frustration, or
> lousy manuals
> > nor missing parts, or wrong parts shall keep me
> from my task.
> >
> > --
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> >
> >
> 
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