[dm-crypt] Variable data offset for a LUKS volume that uses a detached header.
gmazyland at gmail.com
Tue Dec 22 14:44:08 CET 2015
On 12/22/2015 01:00 PM, .. ink .. wrote:
> Happy holidays everybody,
> I am trying to create a LUKS volume with a detached header that has
> data offset at sector 256 and things fail with
> an error that reads:
> "Data offset for detached LUKS header must be either 0 or higher than
> header size (4036 sectors)."
> Is there a technical reason why this is so and is it possible to allow
> other data offsets?
The reason was that it allows header to copy back to the LUKS device.
(Or create a fake header :)
TBH this is the first time I see someone want to use it for Veracrypt
device, I can fix the code to allow it but not sure if this is really
worth to do it.
You can probably write a script that will modify final mapping using
dmsetup (but that's quite a hack). Also simple program should be able
to reformat header to downgrade the header (keep keys and cipher chain).
But wouldn't be better just to use old TrueCrypt modes here from
> Reason for doing this is an attempt at having a detached LUKS header
> capable of unlocking a VeraCrypt volume since
> unlocking a VeraCrypt volume takes too long and its annoying.
> Everything seems to be working except for the data offset since i cant
> set it to 256 sectors through the library API.
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> dm-crypt at saout.de
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