john-users - Re: about salts

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Date: Wed, 05 Apr 2006 14:32:26 -0500
From: Dennis Olvany <dennisolvany@...il.com>
To:  john-users@...ts.openwall.com
Subject: Re: about salts

I have a good idea of the function of salts. Wikipedia summed it up 
pretty well, "Since the salt is different for each user, the attacker 
can no longer use a single encrypted version of each candidate password."

http://en.wikipedia.org/wiki/Password_cracking#Salting

Ok, I've got a good handle on base64 now. So, what's stored in the 
passwd file is a base64 encoding of the hash. I've confused myself 
again, though. A 13 character encoding of which the first two characters 
are the salt. At 6 bits per character, that makes the salt 12 bits and 
the hash 66 bits. DES is 56 bits, no?

Possibly there is a resource that provides such details specific to 
password hashes. Something that maybe covers many hashes and details the 
salts and encodings.

Many thanks for the answers so far, Solar. I'm learning some good stuff 
here.