phc-discussions - Re: [PHC] wider integer multiply on 32-bit x86

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Mon, 3 Mar 2014 18:23:32 -0800
From: Andy Lutomirski <luto@...capital.net>
To: discussions <discussions@...sword-hashing.net>
Subject: Re: [PHC] wider integer multiply on 32-bit x86

On Mon, Mar 3, 2014 at 6:13 PM, Solar Designer <solar@...nwall.com> wrote:
> I think 4 instructions, including the loads and stores, for a 63x63->63
> multiply is rather good.  Without this trick, it'd take 4 _multiplies_
> to implement the equivalent via 32x32->32 (or perhaps 3 multiplies if we
> also use the 32x32->64).  Some bigint library could use this trick,
> perhaps for some nice speedup on those older CPUs/builds (does any use
> it already?)

I think that Poly1305 and related things use a similar trick, at least
on some architectures.

Silly question, though: why are i387 instructions better than SSE2 here?

--Andy