john-users - working with large files

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Date: Fri, 25 Apr 2008 14:22:14 +0200
From: Simon Marechal <simon@...quise.net>
To: john-users@...ts.openwall.com
Subject: working with large files

Hello,

	I noticed that john slows down a lot when working with unsalted large 
password files. It spends all its time at first in the functions that 
are called when a password is found:

Each sample counts as 0.01 seconds.
   %   cumulative   self              self     total
  time   seconds   seconds    calls   s/call   s/call  name
  53.99     35.69    35.69     1120     0.03     0.03  ldr_update_salt
  26.55     53.24    17.55     1119     0.02     0.05  crk_process_guess
  12.63     61.59     8.35   884044     0.00     0.00  ldr_load_pw_line
   4.18     64.35     2.76 817642756     0.00     0.00  binary_hash3


This really isn't cool. I already increased the size of the values 
returned by binary_hash and stuff like that. However, it would be really 
useful to be able to speed up the ldr_update_salt function. Has anybody 
a suggestion on how to do this in a clean way?

PS: I couldn't give it much thought, but i guess that replacing 
ldr_update_salt by a piece of code in crk_process_guess that removes the 
found password in the next_hash chain would be enough to gain much 
speed. Would there be side effects?

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