Is "cryptsetup" needed when changing files "crypttab" and "fstab" manually?
Solution 1:
I bet you still have a libcryptsetup package:
https://packages.ubuntu.com/hirsute/libcryptsetup12
Systemd have its own builtin executable, which makes use of the library, that it uses to handle crypttab entries:
https://github.com/systemd/systemd/blob/main/src/cryptsetup/cryptsetup.c
https://www.freedesktop.org/software/systemd/man/[email protected]
P.S. It might be worth mentioning that, if you have an encrypted root filesystem, and your initramfs init isn't systemd, you'll still need cryptsetup-bin et. al. to open/unlock the encrypted block device.