john-users - Re: Cracking SHA1 with some knowledge of password

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

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Date: Fri, 8 Feb 2013 21:36:50 +0100
From: magnum <john.magnum@...hmail.com>
To: john-users@...ts.openwall.com
Subject: Re: Cracking SHA1 with some knowledge of password

You could use an external filter but it will have crappy performance for a fast raw hash like this.

Unfortunately you can't use rules with Incremental mode. I have considered trying to enable that. Should be trivial.

Jim's idea is your best bet.

magnum


On 8 Feb, 2013, at 21:01 , Lex Par <ziptied@...il.com> wrote:

> Thanks! Is there a way to do this without using a word list (brute force
> it)?
> 
> Thanks.
> 
> On Fri, Feb 8, 2013 at 2:16 PM, magnum <john.magnum@...hmail.com> wrote:
> 
>> On 8 Feb, 2013, at 17:40 , Lex Par <ziptied@...il.com> wrote:
>> 
>>> Group, I have a SHA1 hash that I would like to brute-force. I have
>>> knowledge of several characters before and after the password (ie, if the
>>> hash is derived from "xxxpasswordyyy", I know both xxx and yyy).  I'd
>> like
>>> to somehow input the xxx and yyy values as constants, so that they are
>>> always included in the crack attempt but the "password" portion is
>>> brute-forced.
>> 
>> This can be done in several ways but using rules should be fastest. Add
>> this to your john.local.conf:
>> 
>> [List.Rules:custom]
>> A0"xxx"Az"yyy"
>> 
>> 
>> Then run wordlist mode with --rules:custom.
>> 
>> magnum
>>