[dm-crypt] Using plain64/plain IV (initialisation vector) in dm-crypt

Arno Wagner arno at wagner.name
Tue Jul 27 21:37:23 CEST 2010

On Tue, Jul 27, 2010 at 08:59:24PM +0200, Christoph Anton Mitterer wrote:
> On Tue, 2010-07-27 at 17:55 +0200, Milan Broz wrote:
> > I tried to not mix that XTS/XEX 1TB problem with plain IV explanation,
> > so it should read "1TB data limit is different problem not related
> > to plain/plain64 IV limit"
> > (I changed subject to mention IV only - but forgot to mention it.)
> > 
> > Sorry for confusion:-)
> No problem,.. but if there is another problem,... which means one cannot
> have >1TB (Rogaway 2004 mentioned by Mario),... we should add that to
> the FAQ (that people should not create larger devices), and perhaps give
> a warning when doing so...

First, this is a soft limit, and it becomes a real concern 
at around 1000TB. And second, it affects all ciphers with 
128 bit block size, as far as I understand the issue, and
hence is not anything specific for our case.

So, no, not an FAQ item IMO.


Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno at wagner.name 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans

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

More information about the dm-crypt mailing list