Unfortunately, an encrypted home partition in Ubuntu 22.04 is not going to be unencrypted by default unless someone does some tricky preparations. Even if one does, it will not be possible to use it as HOME partition again as it was before. Or at least I haven't found the solution.
The developer of Ubuntu 22.04, Cannonical Ltd., has decided to use fscrypt as a file encryption tool for file systems, which means that they turned away from encFS or LUKS. The tool fscrypt is developed by Google, it has kernel level implementation, so it is very fast and has a huge user base on Android. It runs w/o problems unless you want to reinstall your OS.
The documentation (https://github.com/google/fscrypt) says at a point:
pam_passphrase (login passphrase) protectors are a bit different as they are always stored on the root filesystem, in /.fscrypt. This ties them to the specific system and ensures that each user has only a single login protector. Therefore, encrypted directories on a non-root filesystem can't be unlocked via a login protector if the operating system is reinstalled or if the disk is connected to another system -- even if the new system uses the same login passphrase for the user.
From this I have concluded that if I backup /.fscrypt from the old OS and restore in the reinstalled OS, I would be able to mount and unlock the HOME partition... but I was wrong. It is not possible.
I could only unlock my home folder by means of the automatically generated a recovery passphrase in file fscrypt_recovery_readme.txt , with the help of a so-called "custom protector" like this:
root@mate:/home/.fscrypt/protectors# fscrypt status /home
PROTECTOR LINKED DESCRIPTION
d7ca0ea34767xxxx No custom protector "Recovery passphrase for user1"
0a2d3b01016fxxxx No login protector for user1
POLICY UNLOCKED PROTECTORS
bd48e9a4e3166c37e806a300bf5cxxxx Yes 0a2d3b01016fxxxx, d7ca0ea34767xxxx
Does anybody know how to backup all security keys of fscrypt, reinstall Ubuntu 22.04, and revive access to the home partition with the backed up security keys?
