Re: [Qemu-devel] Can I mount encrypt qcow2?

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, Jul 20, 2017 at 05:07:49PM +0800, 陳培泓 wrote:
> oh~ I don't know can expose the LUKS encryption. I'm sure the older(AES)
> can't be mounted by qemu-nbd.

It can be mounted, with current git master (all the commands I show
below are for git master btw).

You should, however, *never* use the old AES format any more. It is
broken by design and not considered secure.

> If I encrypt by the command you recommended:
> 
> > qemu-nbd --object secret,id=sec0,file=passwd.txt,format=raw \
> >              --image-opts driver=qcow2,file.filename=
> > demo.qcow2,encrypt.format=luks,encrypt.key-secret=sec0

This *is* exposing the encrypted file -  not creating it. If you
want to connect to a host nbd device then you use the command
above, with the -c arg

$ qemu-nbd --object secret,id=sec0,file=passwd.txt,format=raw \
           -c /dev/nbd0 \
           --image-opts driver=qcow2,file.filename=demo.qcow2,encrypt.format=luks,encrypt.key-secret=sec0


If you have a legacy AES qcow2 file the syntax is very similar

$ qemu-nbd --object secret,id=sec0,file=passwd.txt,format=raw \
           -c /dev/nbd0 \
           --image-opts driver=qcow2,file.filename=demo.qcow2,encrypt.format=aes,encrypt.key-secret=sec0

Note we just changed the encrypt.format parameter there.


To actually create an encrypted file in the first place you need the
qemu-img command

$ qemu-img create --object secret,id=sec0,file=passwd.txt,format=raw \
           -f qcow2 -o encrypt.format=luks,encrypt.key-secret=sec0 \
	   demo.qcow2 1G
  

Regards,
Daniel
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