Re: [dm-crypt] cryptsetup, LUKS, plausible deniability

[Arno Wagner <arno@wagner.name>]

On Mon, Sep 14, 2009 at 01:25:48PM +0200, Mario 'BitKoenig' Holbe wrote:
> Arno Wagner <arno@wagner.name> wrote:
[...]
> > If you want more, use TrueCrypt, but I would be very careful
> > with plausible deniablility anyways. Your protection is primarily
> > that they cannot force you to give up your keys. If you live
> > in a country were they can, I propose to very seriously consider
> > leaving that country for good. See also http://xkcd.com/538/
> 
> That's exactly the reason for plausible deniability. You know they are
> able to force you to give them your key(s), so you prepare some keys to
> give them (along with some data which makes some sense to be encrypted)
> and the system gives you the ability to plausibly deny the existence of
> more keys. Just in the hope they stop cutting your extremities after the
> 6th finger because you convinced them.

I would say plausible deniability has the potential to make
them continue even after you have given them everything, after
all you could have hidden more with the "plausible deniability
thing". 

On a related note, there has been a lot of evidence that
torture does not work (foremost the French in Aleria, that 
failed to find the headquaters of the resistance for years,
despite torturing resistance fighters). For one thing people
are likely to give you false information. This leads me to the
conclusion that most torturers and their bosses are actually
not interested in information, but in the cruelty itself. 

So I would say that plausible deniability is of very low value
in practice and may have potential negative value in some
situations. With plausible deniability they are sure to 
torture you untill you are completely broken, while without 
it, you can give them everything in a way they can actually
verify. It is possible that you have information that still
merits being protected under these circumstances, but I don't.
Plausible deniability basically assumes the life of the person
having the key is worth less than the information.

Arno 
-- 
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@wagner.name 
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