Plain dm-crypt encrypts the device sector-by-sector with a
single, non-salted hash of the passphrase. No checks are
performed, no metadata is used. There is no formatting operation.
When the raw device is mapped (opened), the usual device
operations can be used on the mapped device, including filesystem
creation. Mapped devices usually reside in /dev/mapper/<name>.
The following are valid plain device type actions:
open --type plain <device> <name>
create <name> <device> (OBSOLETE syntax)
Opens (creates a mapping with) <name> backed by device
<device>.
<options> can be [--hash, --cipher, --verify-passphrase,
--sector-size, --key-file, --keyfile-offset, --key-size,
--offset, --skip, --size, --readonly, --shared,
--allow-discards, --refresh]
Example: 'cryptsetup open --type plain /dev/sda10 e1' maps
the raw encrypted device /dev/sda10 to the mapped
(decrypted) device /dev/mapper/e1, which can then be
mounted, fsck-ed or have a filesystem created on it.
