Re: [Qemu-devel] QCOW2 cryptography and secure key handling

[Stefan Hajnoczi <stefanha@gmail.com>]

On Tue, Jul 23, 2013 at 04:40:34PM +0200, Benoît Canet wrote:
> > More generally, QCow2's current encryption support is woefully inadequate
> > from a design POV. If we wanted better encryption built-in to QEMU it is
> > best to just deprecate the current encryption support and define a new
> > qcow2 extension based around something like the LUKS data format. Using
> > the LUKS data format precisely would be good from a data portability
> > POV, since then you can easily switch your images between LUKS encrypted
> > block device & qcow2-with-luks image file, without needing to re-encrypt
> > the data.
> 
> I read the LUKS specification and undestood enough part of it to understand the
> potentials benefits (stronger encryption key, multiple user keys, possibility to
> change users keys).
> 
> Kevin & Stefan: What do you think about implementing LUKS in QCOW2 ?

Using standard or proven approachs in crypto is a good thing.  I haven't
looked at qcow2 encryption in the past because fairly few people
actually use it.

One use-case I have heard about is qcow2 files over NFS.  The network
and the storage system should not see guest data.  Only the host and the
VM should see the data.

A big win with LUKS is that you can change the passphrase without
re-encrypting the data.

Stefan