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Device-Mapper's "crypt" target provides transparent encryption of block devices
using the kernel crypto API.
Parameters: <cipher> <key> <iv_offset> <device path> <offset>
Encryption cipher and an optional IV generation mode.
(In format cipher[:keycount]-chainmode-ivopts:ivmode).
/proc/crypto contains supported crypto modes
Key used for encryption. It is encoded as a hexadecimal number.
You can only use key sizes that are valid for the selected cipher.
Multi-key compatibility mode. You can define <keycount> keys and
then sectors are encrypted according to their offsets (sector 0 uses key0;
sector 1 uses key1 etc.). <keycount> must be a power of two.
The IV offset is a sector count that is added to the sector number
before creating the IV.
<device path>
This is the device that is going to be used as backend and contains the
encrypted data. You can specify it as a path like /dev/xxx or a device
number <major>:<minor>.
Starting sector within the device where the encrypted data begins.
Example scripts
LUKS (Linux Unified Key Setup) is now the preferred way to set up disk
encryption with dm-crypt using the 'cryptsetup' utility, see
# Create a crypt device using dmsetup
dmsetup create crypt1 --table "0 `blockdev --getsize $1` crypt aes-cbc-essiv:sha256 babebabebabebabebabebabebabebabe 0 $1 0"
# Create a crypt device using cryptsetup and LUKS header with default cipher
cryptsetup luksFormat $1
cryptsetup luksOpen $1 crypt1