Re: [Qemu-devel] blobstore disk format (was Re: Design of the blobstore)

[Michael S. Tsirkin]

On Wed, Sep 21, 2011 at 09:44:37PM -0400, Stefan Berger wrote:
> On 09/19/2011 03:04 PM, Michael S. Tsirkin wrote:
> >On Mon, Sep 19, 2011 at 12:22:02PM -0400, Stefan Berger wrote:
> >>On 09/17/2011 03:28 PM, Michael S. Tsirkin wrote:
> >>>On Fri, Sep 16, 2011 at 12:46:40PM -0400, Stefan Berger wrote:
> >>
> >>The checksuming I think makes sense if encryption is being added so
> >>decryption and testing for proper key material remains an NVRAM
> >>operation rather than a device operation.
> >Not sure how this addresses the question of what to do
> >on checksum failure.
> >
> Checksum failure on an unencrypted blob would mean that the blob is
> corrupted. In case of encryption 'corrupted' would overlap with a
> 'badly decrypted' blob. In either way the startup of the device
> cannot happen.

With corruption - why not? A specific block being corrupted does not mean all
data is lost.

> We could refuse the NVRAM key suggesting that likely
> this is the wrong key for decryption but corruption is also
> possible.

I'm guessing that if we find a correct ber structure in the file, this
most likely means the key is correct.

-- 
MST