The LUKS headers. If those are corrupted you can’t decrypt the drive. The good news is that you can back up the headers to prevent that from happening.
Those aren’t files, though, they are just some sectors on your block device. Sure, if you mess with those, your ability to decrypt your disk goes out the window, but then, when was bypassing the filesystem and messing with bits on your disk directly ever safe?
It’s possible he was using an encrypted key file instead of just a password for that extra strong security. In that case, of course, if you lose that file, kiss your data good bye.
The LUKS headers. If those are corrupted you can’t decrypt the drive. The good news is that you can back up the headers to prevent that from happening.
Those aren’t files, though, they are just some sectors on your block device. Sure, if you mess with those, your ability to decrypt your disk goes out the window, but then, when was bypassing the filesystem and messing with bits on your disk directly ever safe?
It’s possible he was using an encrypted key file instead of just a password for that extra strong security. In that case, of course, if you lose that file, kiss your data good bye.