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Reducing password lists with password policies

When cracking passwords, efficiency is everything. You've spend hard earned money on GPUs, you may as well optimise your password lists to make sure that you don't waste time hashing passwords that are out of policy for your target organisation.

So that's simple enough with a few grep and sed commands but after a while you start to feel lazy and script it. Thats why I've added  password policy script to my password munging script.

Using the policy script is pretty straightforward:

./policy.py -luns passwords.txt -o passwordsinpolicy.txt

The switches are as follows:
-l --lowercase passwords must include lowercase letters
-u --uppercase passwords must include uppercase letters
-n --numeric password must include numbers
-s --special passwords must include special characters

All of the above are switched on by default.
The input file must have each password on a separate line.

There are also the following optional switches:
-m --min minimum password length
-M --mx maximum password length
-r number of rules to match
I've found that this script only reduces the password list by 10-20% but a good number of those are the simpler ones that get tried first so that tends to be 10% off the front of cracking time rather than 10% off the end of cracking time.

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