john-users - Re: Sha-256

Openwall GNU/*/Linux 3.0 - a small security-enhanced Linux distro for servers
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Date: Sat, 30 Jul 2011 08:59:49 -0500
From: "JimF" <jfoug@....net>
To: <john-users@...ts.openwall.com>
Subject: Re: Sha-256

From: "groszek" <necro@...icon.pl>
>
> Oh, very nice!
> JTR development has gained quite a momentum recently. Just updated to
> 1.7.8-jumbo-4, dropped my files in there and it Just Works, sweet.

It is.  Magnum and I know that Alex was a little hesitant on releasing the 
'plugin' format, as it was a somewhat intrusive change, even if it was ONLY 
file name changes.  Then, there was also a short period of growing pains, 
trying to get things working properly, but hopefully that has been worked 
through.  But yes, it really IS that easy, and sweet to be able to focus on 
the format, and not have to worry about digging into the guts of john, to 
try to get your work running properly.

Also, along the same line of thinking, it is also very easy to remove 
formats that are having problems with building/running on some older system. 
If a format causes john to crash, and you do not know how, or have time to 
fix it, you can simply rename that file to something like *_fmt_plug_bak.c 
and rebuild john, and bingo, you have a john, with that problem format 
removed.  Then a simple post stating that "format XYZ fails on my sinclair 
ZX80000 but I do not know how to fix it" post, and someone, will likely get 
it fixed at some time.  But in the mean time, john will work for you, and 
you can still run -test or the make test (to run the test suite), and john 
will simply skip right over that crashing format.

I do believe there are others out there, who would feel comfortable enough, 
and have the knowledge to be able to add certain hashing algorithms which we 
do not have today, by being able to modify an existing format that is 
'close', and simply adding/chaning the logic so that it handles the hash. 
Being able to do that, and simply releasing that work, without needing to 
understand anything about the plumbing in the bowels of john, or worrying 
about a diff patch or anything.  Releasing to the world is pretty easy also. 
Simply post the original source file (gzip'ed) to the wiki, and install 
instructions simply state to drop the file into john's ./src directory. 
No mess, very easy to do.

The caveat to the plugin layout, is if a format requires library changes, or 
is a non-hash format (like the recent additions of Dhiru), which will 
require additional work.

It really is a win-win, and allows people to focus on the format itself, and 
not the mechanics.  It is GREAT to see new formats arriving, and put into 
John.  Now, I need to get the test suite to be able to work with them, lol.

Jim.