LUKS in-place conversion tool

 luksipc is a tool to convert (unencrypted) block devices to
 (encrypted) LUKS devices in-place (therefore it's name LUKS in-place
 conversion). This means the conversion is performed without the need
 of copying all data somewhere, recreating the whole disk (i.e. create
 a LUKS device, create a new filesystem on the mapped LUKS device, copy
 all data back). Instead, the process is reduced to:
 .
  1. Unmounting the filesystem
  2. Resizing the filesystem to shrink about 10 megabytes (2048 kB is
     the current LUKS header size -- but do not trust this value, it
     has changed in the past!)
  3. Performing luksipc
  4. Adding custom keys to the LUKS keyring