john-users - inconsistent number of cracked hashes in dynamic

Openwall GNU/*/Linux 3.0 - a small security-enhanced Linux distro for servers

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

Date: Sat, 07 Apr 2012 23:29:06 +0200
From: arcctgx <arcctgx@...zta.onet.pl>
To: john-users@...ts.openwall.com
Subject: inconsistent number of cracked hashes in dynamic_6

Dear all,

I ran into a problem with the dynamic_6 format in john-1.7.9-jumbo5. I 
was trying to crack a list of hashes using the password.lst dictionary 
provided with john-1.7.9.

john-1.7.8-jumbo7 cracked 64 hashes from the list:

 > john -for="md5_gen(6)" -w=password.lst hashes.txt
Loaded 443 password hashes with 443 different salts ( md5_gen(6): 
md5(md5($p).$s)  [SSE2 16x4x2 (intr)])
  <snip>
guesses: 64

But john-1.7.9-jumbo5 did not:

 > john -for=dynamic_6 -w=password.lst hashes.txt
Loaded 443 password hashes with 443 different salts (dynamic_6: 
md5(md5($p).$s)  [SSE2i 10x4x3])
  <snip>
guesses: 48

What is interesting, after I removed the john.pot file and tried again, 
I got a different number of hashes cracked:

 > rm john.pot && john -for=dynamic_6 -w=password.lst hashes.txt
Loaded 443 password hashes with 443 different salts (dynamic_6: 
md5(md5($p).$s)  [SSE2i 10x4x3])
  <snip>
guesses: 18

I did that many times, and the number of cracked hashes varied from 
session to session. On the other hand, john-1.7.8-jumbo7 always cracks 
exactly 64 hashes.

I tested john-1.7.9-jumbo5 on 4 machines with various CPUs, make targets 
and compiler versions:

Intel Q9550 Core2 Quad, linux-x86-64, gcc-4.2.4
Intel E6750 Core2 Duo, linux-x86-64, gcc-4.6.2
Intel Pentium 4, linux-x86-sse2, gcc-4.5.0
AMD Athlon XP 2000+, linux-x86-mmx, gcc-4.5.3

I got the same behaviour everywhere. Is this a bug, or did I do 
something wrong?

In case anyone else would like to test this, the list of hashes is here: 
http://pastebin.com/NpM5PS56

Best regards,
arcctgx