GNU bug report logs - #38924
Encrypted root volume requires passphrase twice on boot

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Matthew Leach <matthew <at> mattleach.net>
To: bug-guix <at> gnu.org 
Subject: Encrypted root volume requires passphrase twice on boot
Date: Sat, 04 Jan 2020 19:27:27 +0000

Hi Guix!

I've setup guix on two machines each one of them with an encrypted root
partition. However, on boot I'm prompted for my passphrase twice, once
before the grub menu is shown and second after Linux has started and
launched guile as init.

I would expect to have to only enter my passphrase once per boot.

Regards,
-- 
Matt

Message #8 received at 38924 <at> debbugs.gnu.org (full text, mbox):

From: Tobias Geerinckx-Rice <me <at> tobias.gr>
Cc: Jakub Kądziołka <kuba <at> kadziolka.net>,
 38924 <at> debbugs.gnu.org
Subject: Re: bug#38924: Encrypted root volume requires passphrase twice on boot
Date: Sat, 04 Jan 2020 20:56:44 +0100

[Message part 1 (text/plain, inline)]

Matthew,

Matthew Leach 写道：
> I've setup guix on two machines each one of them with an 
> encrypted root
> partition. However, on boot I'm prompted for my passphrase 
> twice, once
> before the grub menu is shown and second after Linux has started 
> and
> launched guile as init.

Unfortunately, this is expected.

GRUB needs to decrypt the volume to load the Linux-Libre kernel 
and initrd, and there's no agreed-upon secure way for GRUB to pass 
the passphrase or key to the kernel/initrd.  So you're prompted 
for it again when the volume is actually mounted by the kernel.

> I would expect to have to only enter my passphrase once per 
> boot.

Most distributions hack around this limitation by including the 
unencrypted LUKS key in the initrd on the encrypted volume itself. 
Guix doesn't currently have any code to do the same.

This has been a problem for years but, by sheer coincidence, Jakub 
Kądziołka (CC'd) mentioned that this was on their to-do list for 
next week.

Kind regards,

T G-R

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