Sometimes, it’s worth to encrypt swap space, especially if you process some privacy-sensitive data.

# install cryptsetup
sudo apt-get install cryptsetup
 
# generate swap
sudo truncate -s 1GB /cryptswap
sudo mkswap /cryptswap
 
# add to /etc/crypttab
cryptswap /cryptswap /dev/urandom swap
 
# add to /etc/fstab
/dev/mapper/cryptswap none swap sw 0 0
 
# activate encryption and swap
sudo /etc/init.d/cryptdisks reload && sudo swapon -a

Inspired by AskUbuntu.