[dm-crypt] Encrypt all partitions with dm-crypt

Arno Wagner arno at wagner.name
Fri Aug 24 17:14:39 CEST 2012

On Fri, Aug 24, 2012 at 04:40:28PM +0200, Heinz Diehl wrote:
> On 24.08.2012, Milan Broz wrote: 
> > There is currently a lot of effort to ensure that /dev/urandom
> > cannot produce weak data even in extreme situations.
> I'm more than happy that Intels hardware RNG isn't used as the only
> source for randomness on systems where it is available (as proposed by 
> Linus himself).
> https://patchwork.kernel.org/patch/1161881/

I agree. I think Linux does not quite understand the issue here.
If some Intel chips are compromised, nothing but a very expensive
hardware analysis or a massive intelligence blunder would reveal
that, hence it is very, very unlikely for Intel (or any other
CPU maker) to get caught red-handed.

On the other hand, mixing in a reasonable amount of other 
randomness negates any attack possibilities via the HW RNG
and at the same time allows it to be used as high-quality
"stretching" material. For example, using 512 bits of
other entropy and stretch this to a few MB with the HW RNG 
would still be fine (if done right) even if the HW RNG is 

The solurtion by Tso makes perfect sense cryptographically
and from a risk-management perspective. Never put all your
eggs in one basket unless there really is no other choice.


Arno Wagner,    Dr. sc. techn., Dipl. Inform.,   Email: arno at wagner.name 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
One of the painful things about our time is that those who feel certainty 
are stupid, and those with any imagination and understanding are filled 
with doubt and indecision. -- Bertrand Russell 

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