Installation

$ sudo apt-get install cryptsetup
$ sudo yum install cryptsetup-luks

Setup

Creating a Luks encrypted USB disk

1. Format the device and set the password

   $ sudo cryptsetup -y -v luksFormat /dev/xvdc
   

2. Open the container

   $ sudo cryptsetup luksOpen /dev/xvdc backup
   

3. Verify the mapper has been assigned and the container opened correctly.

   $ ls -l /dev/mapper/backup
   

4. Put a filesystem on it. First zero the partition and the put the FS on it. This can take hours and depends on the size of the disk used and the system resources (2TB took ~20h for me).

   Without Progress bar:

   $ sudo dd if=/dev/zero of=/dev/mapper/backup
   

   With progress bar:

   $ sudo time pv -tpreb /dev/zero | dd of=/dev/mapper/backup bs=128M
   

   Create a FS:

   $ sudo mkfs.ext4 /dev/mapper/backup
   

Maintenance

Status

View the status of a current mapping

    $ sudo cryptsetup -v status backup

Mount

Mount and access the data at /mnt/disk

$ sudo cryptsetup luksOpen /dev/xvdc backup
$ sudo mount /dev/mapper/backup /mnt/disk

Unmount

Unmount the disk and close the container.

$ sudo umount /mnt/disk
$ sudo cryptsetup luksClose backup

Change passphrase

New passphrase needs to be provided.

$ sudo cryptsetup luksDump /dev/xvdc
$ sudo cryptsetup luksAddKey /dev/xvdc

Remove passphrase

The old passphrase needs to be entered.

$ sudo cryptsetup luksRemoveKey /dev/xvdc