Date: Wed, 30 Oct 2013 17:26:15 +0100 From: Katja Malvoni <kmalvoni@...il.com> To: john-dev@...ts.openwall.com Subject: Re: ZedBoard: bcrypt On Wed, Oct 30, 2013 at 4:12 PM, Solar Designer <solar@...nwall.com> wrote: > On Wed, Oct 30, 2013 at 03:50:06PM +0100, Katja Malvoni wrote: > > On Wed, Oct 30, 2013 at 2:07 PM, Katja Malvoni <kmalvoni@...il.com> > wrote: > > > On Wed, Oct 30, 2013 at 10:17 AM, Solar Designer <solar@...nwall.com > >wrote: > > >> If so, does anything prevent you from optimizing this to? - > > >> > > >> Cycle 0: compute new R; swap L and R; initiate 4 S-box lookups > > >> Cycle 1: wait > > >> > > >> ... except possibly for the special cases of the first and the last > > >> round? In the first round, bypass some of the logic. After the last > > >> round, invoke the same logic, but bypass the S-box lookups. > > > > > > As far as I can tell nothing prevents me to do that, I'm on it now. > > > > Actually I can't do that - I need L to know which element from S-box to > > fetch > > Sure. > > > and I have to compute it one cycle before initiating S-box lookups. > > Why can't you compute it on the same cycle when you initiate the S-box > lookups? You just need to have the address lines to the BRAM settle > before the clock signal transition, no? Yes, you're right, I made a mistake. L is a register so I'm able to read computed value only on the next rising edge but I should be able to compute corresponding byte from BRAM output lines. Although it still doesn't work in simulation - I must have a bug somewhere. Katja Content of type "text/html" skipped
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