Customizing LVM disk encryption splash logon screen

Question

I just installed Kubuntu, and turned on full disk encryption and LVM.

By default when booting up this machine I now get asked for my password twice. The first time is a relatively ugly boot splash to decrypt the drive (I think). The second time is the normal GUI logon where you choose which user you want.

Is this what's supposed to happen? (I don't want it to happen.)

If not, how can I fix it so I only get the normal logon?

If yes, is there any way to customise the decryption splash? e.g. so that it says

Welcome Matthew

instead of

Please unlock disk sda5_crypt

printscreens

pretty logon

ugly logon

Answer 1

These are password prompts for two different passwords. Since the system cannot assume that the passwords are equal, it will have to ask for both separately.

Secondly, the first password is required to unlock the main partition containing the operating system, which in turn contains (a hashed version of) your user login credentials. Thus, it has to be asked for first, and since the main OS has not be loaded yet, there is no easy way to show a "nice" password prompt, nor any way to know that there exists a user "Matthew" on the system.

You can change the first password prompt a bit, by editing /lib/cryptsetup/cryptdisks.functions as root, see http://ubuntuforums.org/showthread.php?t=2128704, but I would warn against that, unless you really know what you are doing.

What you could do, is disable the second password prompt by automatically logging you in into the graphical system, see e.g. https://askubuntu.com/questions/538462/auto-login-with-kubuntu-14-10-kde-5-plasma