This is useful e.g. if the keyfile is a raw device, where only parts of it
should be read. It is typically used whenever the keyfile-offset= option is
specified.
Tested-by: Erik Westrup <erik.westrup@gmail.com>
This is useful if your keyfile is a block device, and you want to
use a specific part of it, such as an area between the MBR and the
first partition.
This feature is documented in the Arch wiki[0], and has been supported
by the Arch initscripts, so would be nice to get this into systemd.
This requires libcryptsetup >= 1.4.2 (released 12.4.2012).
Acked-by: Paul Menzel <paulepanter@users.sourceforge.net>
[0]:
<https://wiki.archlinux.org/index.php/System_Encryption_with_LUKS#
Storing_the_key_between_MBR_and_1st_partition>
