I've just switched to Ubuntu 12.04 one year ago and moved all my photos, documents, etc to the 1TB main hard drive that has been encrypted during the installation process - not LVM but only the home folder.
I didn't record any key or passphrase when prompted... However, it only required the password to login in the system and have access to the files.
It happened that after one month of holiday I've forgotten my password so I've googled and found a way to change it:
from the recovery mode, I've selected the root shell and at the prompt I entered:
mount -rw -o remount / passwd <username> init 2
Desperately I've tried lots of passwords.. and after a while I've found the initial password written down.
I've set this password back again and now the system doesn't want to start up Ubuntu - it only loops in between the login screen - it doesn't say "Invalid password" - and a black screen and then back to the login screen.
So the system cannot decrypt the hard drive.
Could it be that the "init 2" has deleted some sort of info?
Looks like something has been altered by these password changes...
What could be done to recover my data? I know that Kali linux has an utility to decrypt WiFi by "listening" it. Could I use a similar program to find the passphrase?