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Date: Mon, 27 Feb 2012 00:42:09 +0100
From: magnum <>
Subject: Re: -ext:keyboard with 8-bit chars

On 02/26/2012 11:52 PM, Solar Designer wrote:
> On Sun, Feb 26, 2012 at 06:11:20PM +0100, magnum wrote:
>> I tried making a custom keyboard external mode for producing German
>> keyboard output in iso-8859-1. I doubled the array sizes per the comment
>> and also changed the while loop that initializes mc accordingly. At
>> first I just entered the characters as 'ß' and so on, and took care that
>> john.conf was encoded in iso-8859-1. But I got a segmentation fault when
>> running. (...)
> It's neither a bug nor a known limitation - I was not aware of it

...enlightening explanation snipped here because I have no follow-up
questions - but thanks!

> (...) we may want to have it behave the way a C implementation would
> for char being unsigned (also valid) - this may be more convenient
> for us, as you have found out. To make this change, you may e.g. edit
> the two instances of "value = c_getchar(1)" to "value = (unsigned
> char)c_getchar(1)" in c_getint(). I did not test this change.

I just tested this, it works fine too.

>> Another thing, the comment "This sample can be enhanced to infer the
>> rest of the indices here". What exactly is missing, and what would it
>> change? Are we not resuming correctly with current code?
> We only infer the length and id[0], but not id[1] and on (they're now
> set to 0).  This means that when we interrupt and --restore a Keyboard
> mode run, it tries some previously-tested candidate passwords for a
> second time.

I don't really get the flow, but I suppose the worst-case scenario can
be quite bad for a slow hash interrupted after a long run? If so, I
think it's worth implementing but I have no idea how to do it.


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