I followed the instructions at Transparent Encryption For a User's Home Folder to encrypt my home folder.
It all worked except the last command:
sudo ecryptfs-setup-swap
returned:
Unknown device "/dev/var/swap": No such file or directory
cannot open /dev/mapper/cryptswap1: No such file or directory
cannot open /dev/mapper/cryptswap1: No such file or directory
My guess is that is because Raspberry Pi OS does not have a SWAP partition.
According to: How to set up swap space? Raspberry Pi OS has a SWAP file.
I'm not exactly sure what to do now. My reason for wanting to encrypt SWAP was to prevent data from my home directory being leaked and saved unencrypted on the sd card.
How do I encrypt the SWAP file?
I could disable SWAP altogether but I'm concerned what effect that may have on performance.
*1
According to the comments at How to change Raspberry Pi's Swapfile Size on Raspbian the number 0 sets SWAP to infinite. Meaning, 0 does not disable SWAP (for those interested in disabling SWAP altogether)