Completely encrypt your external HDD / USB-Key securely using Ubuntu Linux

If you ever wondered how to encrypt some external devices in Ubuntu or Linux in general, the following commands will guide you:

1. Create a crypted LUKS container for your device (replace /dev/xxx with your device):    

sudo cryptsetup --cipher aes-xts-plain64 --key-size 512 --hash sha512 --iter-time 5000 --use-random --verify-passphrase luksFormat /dev/xxx

You can also spare the additional parameters, cryptsetup will fall back on the default  parameters. Further explanation of what each parameter means can be found here.  

2. Open you encrypted container:    

sudo cryptsetup luksOpen /dev/xxx crypt_container    

3. Create a file system within the opened container (e.g. ext4):

sudo mkfs.ext4 /dev/mapper/crypt_container


4. Close the container and unmount it:    

sudo cryptsetup luksClose crypt_container     
sudo umount /dev/xxx    

That's it. Finally, if you disconnect and replug you device, Dolphin or Nautilus  will ask you for you password and mount it as every standard device.   If you need to check your new encrypted device or partition for errors, read this.