Re: Re-encrypting using multi-key (was Re: Upgrading to a 2.6 Kernel on a Loop-AES Machine)

[Jari Ruusu <jariruusu@xxxxxxxxxxxxxxxxxxxxx>]

"Eloy A. Paris" wrote:
> On Wed, Jul 21, 2004 at 04:28:10PM +0300, Jari Ruusu wrote:
> > Mainline cryptoloop only does single-key mode, which has been broken.
> > Since your root partition is using single-key mode, your setup is also
> > broken. Re-encrypting using loop-AES multi-key mode is the way to go.
> 
> You bring up something I have been meaning to ask for a long time, but
> keep forgetting: my hard drive is encrypted using single-key mode. What
> is the recommended way of re-encrypting using multi-key mode? Does it
> require booting with a rescue disk (Knoppix, for example) and using
> aespipe? Any pitfalls to look for?

1) Make sure that loop code (loop.o/loop.ko or kernel patch) is from any
   loop-AES-v2.X version. Module must be copied to /boot/modules-XXXX/
   directory, where XXXX is kernel version.

2) Make sure that mount+losetup+swapon programs are from loop-AES-v2.X
   util-linux patched version, including /bin/mount /bin/umount
   /sbin/losetup /sbin/swapon and most importantly /boot/losetup

3) Create /boot/rootkey.gpg by running step 9 of README example 7.5.

4) Create new initrd.gz by running steps 10 to 13 of README example 7.5.
   USEGPGKEY=1 must be set in build-initrd.sh config.

5) Boot from rescue CD-ROM

6) Mount /boot partition as /mnt, step 18 of README example 7.5.

7) Run root partition data through two copies of aespipe. First one
   decrypts your single-key encrypted data, and second one encrypts in
   multi-key mode. aespipe version must be aespipe-v2.2a or newer.

    dd if=/dev/hda2 bs=64k \
       | /mnt/aespipe -d -e AES128 -T -S `cat /mnt/seed.txt` -C 100 \
       | /mnt/aespipe -e AES128 -K /mnt/rootkey.gpg -G / -w 120 \
       | dd of=/dev/hda2 bs=64k conv=notrunc

   Above assumes that /dev/hda1 is /boot partition and /dev/hda2 is root
   partition. First aespipe command line parameters must be same that you
   used to encrypt, but with -d option added. Note that there is 120 second
   delay before second aespipe asks for a password (it is that "-w 120"
   option).

8) Clean up by running step 20 of README example 7.5.

Above README file example 7.5. refers to loop-AES-v2.1b version.

-- 
Jari Ruusu  1024R/3A220F51 5B 4B F9 BB D3 3F 52 E9  DB 1D EB E3 24 0E A9 DD

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Linux-crypto:  cryptography in and on the Linux system
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