[dm-crypt] question regarding Sha1 and 512 bit key xts mode

Arno Wagner arno at wagner.name
Sat Aug 22 16:05:45 CEST 2015

On Sat, Aug 22, 2015 at 12:04:08 CEST, Michael Kjörling wrote:
> That's not to say that LUKS is invulnerable, especially in practice.
> It does however make it seem likely that an adversary would pick a
> different attack. It would be much cheaper, and less obvious, to
> install a key logger, or hire some criminals to kidnap and torture
> your family until you give up the passphrase.

Or maybe expose what websites you were subscribed on to your 
wive, or hack your computer and put some illegal stuff on it 
and threaten to tell the authorities. "Rubber hose" crypto does
not need physical presence anymore these days.

I very much agree, and so does what we observe in practice. The 
crypto can be made hard enough to be secure in the sense that
an attack on it costs far too much. I believe LUKS has that at
this time with the defaults. But the surrounding systems are an
entirely different matter and massively more complex, and even
more so when you leave the computer and include the user.

It is important to allways look at the complete situation in
applied crypto and IT security in general (which is one of the 
main things that makes it so hard) or you end up with a house
that has a 30 centimeter steel door at the front and only
a fly-net at the backdoor. 

Arno Wagner,     Dr. sc. techn., Dipl. Inform.,    Email: arno at wagner.name
GnuPG: ID: CB5D9718  FP: 12D6 C03B 1B30 33BB 13CF  B774 E35C 5FA1 CB5D 9718
A good decision is based on knowledge and not on numbers. -- Plato

If it's in the news, don't worry about it.  The very definition of 
"news" is "something that hardly ever happens." -- Bruce Schneier

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