phc-discussions - Re: [PHC] A must read...

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Message-ID: <CALCETrXhRoy88B7Gm61u+2THYqBdkjuPkJoOxgAQ4vrx8_w56A@mail.gmail.com>
Date: Tue, 14 Jan 2014 23:20:28 -0800
From: Andy Lutomirski <luto@...capital.net>
To: discussions <discussions@...sword-hashing.net>
Subject: Re: [PHC] A must read...

On Jan 14, 2014 11:14 PM, "Solar Designer" <solar@...nwall.com> wrote:
>
> On Tue, Jan 14, 2014 at 09:20:16PM -0500, Bill Cox wrote:
> > On Tue, Jan 14, 2014 at 5:31 PM, Andy Lutomirski <luto@...capital.net>
wrote:
> > > On Tue, Jan 14, 2014 at 2:28 PM, Bill Cox > Out of curiosity, have
you tried MultHash(hash, v[addr], prevV, v[addr
> > > - C]) where C is something like L2 cache size?  It might help to have
> > > even more taps.
> >
> > That's funny because my previous hash function was exactly that,
> > though C was 1.  It did help, and was the version that "passed" the
> > DieHarder tests.  I'd be curious to understand your feeling for why
> > that would work better.  I discovered it through trial and error.
>
> I guess Andy suggested this as an easy way to make some use of L2 cache
> for defense, not as a way to improve randomness.

Yes.  No idea how well it works on modern CPUs -- it probably depends
heavily on the cache replacement algorithm and how many loads can be
pending.

>
> Alexander

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