[dm-crypt] Variable data offset for a LUKS volume that uses a detached header.

.. ink .. mhogomchungu at gmail.com
Wed Dec 23 09:39:44 CET 2015

> Hmm. What about actually shifting the partition contents physically?
The current problem is not on the data offset,but it is on IV offset.

LUKS API allows setting of data offset and i got it to accept 256
sector offset by removing the
current restriction that forces the offset to be either zero or larger
that header

Currently,LUKS API does not have an option to set IV offset and my problem would
be solved if the API is introduced.

> Or maybe have a dummy-LUKS device, open that, read the master-key
> (see FAQ Item 6.10 ) close it again, and use that master-key
> on a plain device? This is probably far to complex, but could
> serve for experiments.

My understanding the API documentation says a pre-generated master key
can be used
with "crypt_format" only with LUKS volumes.

Once the master key and other info are known,the best way to do it is to create
the mapper straight using dmsetup. I can already do this but the
problem with doing
it this way or through plain device is in the management of the master
key and i was
hoping that a detached LUKS header will be able to manage it for me.

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