My latest dumb RPi project is trying to make it boot from a LUKS-encrypted partition. However, I have not succeeded in making this happen. The boot sequence does not ask for a passphrase, throws me into a busybox which does contain cryptsetup, but it doesn't let me actually open the encrypted volume because libgcc_s.so.1 is missing. I basically tried to follow this guide, making substitutions as needed from this other guide for booting from Btrfs (which that part by itself works), but no dice. :/
Solution: include the missing library manually. Shows what I know, I guess.
Now, it's still throwing me into a busybox, and I'm not really sure how to make it just ask for the passphrase during the proper boot process, but I'm at least able to open the encrypted volume from there without any errors.