DM-Crypt

dm-crypt can create and manage encrypted devices.

Creating an encrypted devices

To create a encrypted device simply run:
cryptsetup -y -v luksFormat /dev/sda2.
Where /dev/sda2 is the device you want to create.

Open an encrypted device

To open and map a device run cryptsetup -y -v luksFormat /dev/sda1 crypt0 where
/dev/sda1 is your encrypted device and crypt0 is where it will be mapped to
with dev/mapper/crypt0.