[dm-crypt] LUKS header recovery attempt, bruteforce detection of AF-keyslot bit errors

Dominic Raferd dominic at timedicer.co.uk
Mon Apr 24 07:50:01 CEST 2017

On 23 April 2017 at 21:03, protagonist <listdump at depressiverobots.com>

> On 22.04.2017 20:02, protagonist wrote:
> > I've manually compiled
> ​...​

​This is pretty impressive stuff to someone like me who is new to dm-crypt.
But I wondered if the chances of the passphrase being misrecorded or
misread have been fully considered. In your OP you wrote: 'The password is
fairly simple and contains no special characters or locale-sensitive
characters and had been written down... none of the characters change
between a US layout and the DE layout that was used. There are also no
characters that can be easily confused such as O/0.'

I note the 'written down' but if by this you meant 'recorded in a Word
document', say, then perhaps a capitalisation error has crept in. By far
the most likely is that the first character is recorded as capitalised when
it isn't (as Word likes to capitalise the letter at the beginning of a
sentence).​ Other possibilities include an extra space or spaces (at the
beginning or end?), or a period being read as part or not part of the
passphrase. It would also be worth re-reviewing the possibility that some
characters have been confused - if the passphrase was written down by hand
the chances greatly increase. And to be quite sure it isn't a keyboard
issue, can you try with a DE keyboard?

As it happens a single capitalisation error would be picked up by a brute
force method that tests for a single bit flip...
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