From: Christophe Saout <christophe@saout.de>

Adds a crypto module for device-mapper.  The intent here is to remove
cryptoloop ASAP, to pull the remapping gunk out of the loops driver and to
migrate people onto dm-crypt.  It is on-disk compatible with existing
cryptolop installations.

See http://www.saout.de/misc/dm-crypt/ for usage details.