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Date: Mon, 23 May 2005 14:14:39 -0400
From: "James" <james@...nderdomesystems.com>
To: <john-users@...ts.openwall.com>
Subject: RE: Fastest Crack of known password length
Kind of hard to reset Root ;) As far as big wordlist I've tried that one and
let it run forever it seems (over a week) and since I am pretty sure the
password is not word based it was unable to crack it. This is why I was
thinking of an incremental against a known length of 8.
One PC was set to incremental the other wasn't. Wasn't sure which would get
there first. As far as running it against a single user hash all the users
(well all but a few) have the same hash including root. I figured by setting
it to work just that one hash again it would run a bit faster.
This is somewhat a test to compare various attacks against passwords.
Knowing a Windows sam file takes just minutes to crack 90% of the time
because of weak passwords I wanted to see what John could do against a
harder Linux password file so I got one where I don't know the password so I
can't cheat by being creative in a wordlist.
-----Original Message-----
From: Solar Designer [mailto:solar@...nwall.com]
Sent: Monday, May 23, 2005 12:12 PM
To: john-users@...ts.openwall.com
Subject: Re: [john-users] Fastest Crack of known password length
James,
On Tue, May 17, 2005 at 08:51:36AM -0400, James wrote:
> What is the fastest method of cracking a password of known length
> where the password is:
>
> 1. Linux Shadow file
> 2. DES
> 3. Mostly likely is not word based and includes at least 1 standard
> keyboard character.
> 4. Of a known length or at least do a progressice crack where I try 8,
> that fails then I'll try 9, etc.
You need to realize that the traditional crypt(3) DES-based hashes truncate
passwords longer than 8 characters. So even if you think that your password
is longer, it really is not.
It should be quick enough to run through a wordlist with mangling rules for
just a single traditional DES-based hash, so you do not need to apply any
length restrictions there. Just pick a large enough wordlist (such as the
"all.gz" available off ftp.openwall.com) and do:
./john -w=all.lst -rules pwfile
Then proceed with "incremental" mode. You specify the known length by
setting the MinLen and MaxLen parameters to it. That's done in a section
such as "[Incremental:All]", which you may copy under a different name and
customize. Then pass the new name from the command line, such as:
./john -i=custom pwfile
Where the custom section is:
[Incremental:Custom]
File = $JOHN/all.chr
MinLen = 8
MaxLen = 8
CharCount = 95
(the "$JOHN/..." syntax is for a 1.6.x development version).
> I'm running
>
> john -users:***** -format:DES pwl
That's fine. Please be sure to use a recent development version and build
it with support for MMX or AltiVec (if you're on x86 or PPC) for a
significant speedup.
You shouldn't have to specify the "format" explicitly, although your doing
so doesn't hurt.
> Right now on one PC and
>
> john -users:***** -format:DES -i:ALL pwl
>
> On another.
This doesn't make sense. You have both PCs do the same thing.
> I've edited the ini to sent all min. lengths to 8 but does that do
> what I think?
Yes, perhaps (depending on what you think it does, of course).
Why are you running John against a single password hash, though?
Maybe it'd be simpler to reset the password?
--
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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