What is a password dialog in plymouth? I was currently learning to create plymouth themes/scripts from this link while following the guide i came across the **Plymouth.SetDisplayPasswordFunction** area, and after quite an amount of searching on the internet i got lots of information on creating password dialogs in plymouth themes. I don't understand what is a password dialog doing at such an early phase of booting.I assume that it should show when the GDM has started and plymouth has exited. I am totally confused, please someone explain me what is it in details and what does it do..

Certain cases of disk encryption require you to enter a passphrase during boot to unlock the root partition, else the system can't continue booting, because it can't get its data from disk.

Only the boot partition won't be encrypted (or is unlocked by GRUB), so the kernel and the initramfs can still be loaded. But that alone makes a very poor experience, with only BusyBox as a shell and no files to work with.

Without a Plymouth splash, the password prompt will simply be written on the TTY, e.g. something like this:

![enter image description here](

With Plymouth, you can have a password prompt drawn over the boot splash. Here are some examples:

![enter image description here]( ![enter image description here](

(All images taken from Google Image Search)