[dm-crypt] Encrypted root on Fedora 13

[Heinz Diehl <htd@fancy-poultry.org>]

Hi,

is there any possibility in cryptsetup-1.1.3 to maintain / restore the uuid of an encrypted root
partition on a Fedora 13 system? 

What I've planned to do is to switch the standard encryption the Fedora
installer has put on a laptops root partition from aes-xts-plain to
twofish-xts-plain, because twofish is about 25% faster on this machine.
So I'll boot from CD, take a copy of the root fs, reformat it with the new
specs, and restore from backup. 

However, the uuid of the partition gets changed by this process, and I'm
curious if writing the new uuid into fstab/crypttab/grub.conf is enough 
to boot the system properly. 

I tried to chroot into the Fedora root directory from the boot CD and 
rebuild the initramfs via dracut, but the root partition could not be
found any more. I guess the uuid of the encrypted root partition is
included in the initramfs, which means that I have to build an initramfs 
from the active system, which isn't possible.

So is there a possibility (maybe in cryptsetup) that allows to customize
the uuid? It's possible with xfs_admin to do that, but only the uuid of
the mapped partition, the uuid of the device itself doesn't get changed,
of course.

What am I missing?

Thanks,
Heinz.