How to encrypt a disk partition in Linux

LUKS is the standard for Linux hard disk encryption. The following few commands are all you need to encrypt your next external hard disk or USB key on a Debian-based distribution like Ubuntu.

Installation

Install the required software and load the module into the running kernel without restarting:

sudo aptitude install cryptsetup
sudo modprobe dm_crypt

Drive creation

Set up encryption on the disk and mount it:

sudo cryptsetup luksFormat /dev/sdb1
sudo cryptsetup luksOpen /dev/sdb1 external
sudo mkfs.ext4 /dev/mapper/external
sudo mount /dev/mapper/external /mnt

Mounting

How to mount the drive:

sudo cryptsetup luksOpen /dev/sdb1 external
sudo mount /dev/mapper/external /mnt

Unmounting

How to unmount the drive:

sudo umount /mnt
sudo cryptsetup luksClose external