Re: Detached LUKS header

[elaexuotee]

Chris Marusich <address@hidden> wrote:

> I'm not sure.  On your non-Guix setup, the crypttab exists in the
> initrd, right?  And that initrd exists in the /boot directory on the
> external drive, right?

Yes. Specifically, I am using dracut to generate the initrd and I believe it is
the crypt module that copies crypttab into the cpio. Similary, dracut.conf
ensures the initrd also contains the luks header file.

> Have you looked into how you can customize the initrd in Guix?

Beautiful. That URL you shared gives me a good starting place. Thank you.

> If you figure out a configuration that works, please do share it!

I sure will! Thank you for taking the time to share your thoughts.

> address@hidden writes:
>
> > Anyway, is there a straightforward way to configure a mapping device for 
> > LUKS
> > with a detached header? Otherwise, what's the best way to go about passing
> > command line options to the initrd cryptsetup call?
> >
> > For a little context, I like my drive to look just like random data to a 
> > third
> > party; however, the precence of a LUKS header pretty much defeats plausible
> > deniability of hosting encrypted data. Thus, detached headers.
> >
> > To that end, with my current non-guix setup, I have /boot and grub sitting 
> > on
> > an external drive, with dracut shoving the LUKS header in the initrd. Then
> > crypttab references said header, so the initrd cryptsetup call Just Works 
> > TM.
>
> I'm not sure.  On your non-Guix setup, the crypttab exists in the
> initrd, right?  And that initrd exists in the /boot directory on the
> external drive, right?
>
> Have you looked into how you can customize the initrd in Guix?  It's
> described in the "Initial RAM Disk" section of the manual:
>
> https://guix.gnu.org/manual/en/html_node/Initial-RAM-Disk.html#Initial-RAM-Disk
>
> If I understand your non-Guix configuration right, it sounds like you
> put the initrd on the external drive.  Guix normally installs the initrd
> into the store, and then adds to the Grub configuration file a reference
> to the initrd in the store, like this:
>
> menuentry "GNU with Linux-Libre 5.1.2 (#1, 2019-09-13 22:12)" {
>   search --label --set root
>   linux /gnu/store/mmnl20fg05w8gzzsp4d8dvagmdn1vjil-linux-libre-5.1.2/bzImage 
> --root=root --system=/var/guix/profiles/system-1-link 
> --load=/var/guix/profiles/system-1-link/boot quiet
>   initrd /gnu/store/af8h57i9h77r5q9djvviyy4s2gfbnwq8-raw-initrd/initrd.cpio.gz
> }
>
> So, it might be a little tricky to convince Guix to do the right thing
> for your use case.  Also, I think Grub has the ability to read LUKS
> volumes, but I'm not sure how to configure it.
>
> If you figure out a configuration that works, please do share it!
> Hopefully something in my email is helpful to you.
>
> -- 
> Chris

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