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Date: Mon, 21 Nov 2005 16:11:58 +0300
From: Solar Designer <solar@...nwall.com>
To: john-users@...ts.openwall.com
Subject: Re: Patch: Improved raw-md5 and new format (Post.Office MD5)
David,
I am really sorry it's taken me so long to get back to you on this.
On Wed, Oct 26, 2005 at 05:26:30PM +1000, David Luyer wrote:
> I'd like to submit the attached patch to John the Ripper.
> Please feel free to include the patch on the website or in
> any future version (it is released under the terms of GPL
> version 2).
I've just placed the patch into this FTP directory:
ftp://ftp.openwall.com/pub/projects/john/contrib/
under the name john-1.6.39-rawmd5-pomd5-1.diff.gz (notice that I've
added a "-1" for patch revision number).
I'd like to also link it off the webpage, but for that I prefer it to be
split back into two separate patches for the different hash types.
> The patch:
>
> 1. Improves the performance of raw-md5 around 20% compared
> to the version currently on the website. [1]
That's nice. A lot of further improvements are possible indeed; maybe
I'll redo this stuff myself if I ever integrate it into John. :-)
> 2. Implements the Post.Office MD5 crypt format, which may
> be found in Post.Office and in LDAP directories migrated
> from Post.Office (for example, OpenWave and qmail-ldap
> can support this crypt format).
Please excuse my ignorance, but what's Post.Office? Unfortunately,
Google doesn't want to leave the dot included in the search string, so I
am getting a lot of results for various other post offices.
> [3] Earlier "after" test runs were at 3100K c/s to 3200K c/s
> however this was due to an error in the memset() call
> which didn't show up as the memory was usually already zero.
> It may be possible to improve performance towards these
> levels if the memory can be zero'd faster than it is by
> memset(), for example perhaps a memcpy from memory which
> is already zero?
No, memcpy() is unlikely to be faster. There are other techniques which
might be faster on many systems (e.g., direct assignments to 64-bit
variables, especially interleaved integer/floating-point ones), but
slower on some others.
I do not think you should try to push this pure C non-parallelized
implementation to its limits. Clearly, greater speedups are possible by
interleaving instructions from 2+ instances of MD5 (like it is done in
MD5_std.c) on non-register-starved archs (that is, not on x86) and by
doing 2+ instances of MD5 in parallel on vector registers if those are
available. In fact, people have been doing the latter already.
Thanks,
--
Alexander Peslyak <solar at openwall.com>
GPG key ID: B35D3598 fp: 6429 0D7E F130 C13E C929 6447 73C3 A290 B35D 3598
http://www.openwall.com - bringing security into open computing environments
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