grub-mkpasswd-pbkdf2 ; a misunderstanding.

[sl34x]

Hello to all!
If i create a password derivated from a function for the grub2 bootloader with the command grub-mkpasswd-pbkdf2
and i type for example:

sleax@sleax-laptop:~$ grub-mkpasswd-pbkdf2 -c 2000 -l 100 -s 10
Enter password:  (linux)
Reenter password: (linux)
Your PBKDF2 is grub.pbkdf2.sha512.2000.01FEF59C3660E0297A23.B9CC6FB0EE8D02CF1995A2FD45EC7E6A5E04E2C11247514E101EA2F0EF48C8763488E48D8660C987867A0DE6A6694CD5F03250D4F1345B5337DC2204FDDF47FABB2AA4B1898597833E635369BC443DF7073B60722E642A95C892F6DFCFE3EB62427C0944

well, now i would to say how the system can reverse the code, i.e. how can (after edited grub configs) the system go back to "linux" from that derivated key?
Maybe my question is stupid, but i'm curious!

[sl34x]

Noone can tell me this?

[twipley]

It never goes that way, and it does not get to know the password, never.

What it does is check that the hash of the inputted password matches the stored Grub-config hash.

[twipley]

After thinking about it a little bit: not sure anymore, as there seems to be random salt added to the hashing process.