Laptops are easily lost or stolen and in order to protect your emails, web passwords, encryption keys, etc., you should really think about encrypting (at least) your home directory.

If you happen to have /home on a separate partition already (/dev/sda5 in this example), then it's a really easy process:

  1. Copy your home directory to a temporary directory on a different partition:

    mkdir /homebackup
    cp -a /home/* /homebackup
  2. Encrypt your home partition:

    umount /home
    cryptsetup -h sha256 -c aes-xts-plain64 -s 512 luksFormat /dev/sda5
    cryptsetup luksOpen /dev/sda5 chome
    mkfs.ext4 -m 0 /dev/mapper/chome
  3. Add this line to /etc/crypttab:

    chome    /dev/sda5    none    luks,timeout=30
  4. Set the home partition to this in /etc/fstab:

    /dev/mapper/chome /home ext4 nodev,nosuid,noatime 0 2
  5. Copy your home data back into the encrypted partition:

    mount /home
    cp -a /homebackup/* /home
    rm -rf /homebackup

That's it. Now to fully secure your laptop against theft, you should think about an encrypted backup strategy for your data...