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Date: Wed, 10 Aug 2011 07:27:37 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: "valid character" class

On Tue, Aug 09, 2011 at 02:30:12PM +0200, magnum wrote:
> On 2011-08-09 14:02, Solar Designer wrote:
> >We could also want to introduce a class for control chars, though.
> >By default, it'd cover whatever chars are usually the control ones on
> >terminals - see the DumbForce sample.  However, for example,
> >--encoding=cp1251 will turn most chars in the 0x80 to 0x9f range to
> >non-control, even though they will remain risky to the terminal...
> ...
> >So we'll have ?y for valid and ?O for non-control - similar, but
> >different (as you explained above).
> 
> Good idea, I think we should go with that.

My concern, though, is that I am unsure what use cases we will have for
either of these new classes.  Do you have specific rules you'd like to
add, but can't do it yet?  Are you aware of specific real-world
passwords that this would crack?  So far, all this encodings stuff feels
a bit theoretical.  I guess it will be relevant in the future, but is it
already relevant?  Perhaps it is, but we're yet to see it actually being
used to crack passwords...  I thought we'd see some of that in the
contest, but it seems not.

> >Oh, and we could want to allocate a consecutive range of character class
> >letters (maybe a very small range) for user-defined classes.  Maybe we
> >could use digits rather than letters, but then there won't be automatic
> >complements.
> 
> Do you mean user-defined as in john.conf, so eg. a ?2 class would 
> correspond to characters defined in some section in the config file?

Yes.  Maybe even right in the rule, although then we'd want to split
processing of each rule into two parts (some of it could be precomputed).

Alexander

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