On Jun 21, 2005, at 3:33 PM, Peter_22@xxxxxx wrote:
(i just changed cipher of a 150GB twofish-encrypted partition by
dd'ing
from one loop-device from another..now it's done and not a single
bit
lost ;-))
Interesting point! Loop-aes provides no option to change the key/
password
for a partition. Using dd and two loop-devices is rather risky.
Loop-AES never claimed to do anything for key/password management.
I think that this is the correct approach, as it permits flexibility
in key management procedures. Key management is quite difficult, and
a single policy will not help everyone.
The loop-AES README file has many examples that use GNU Privacy Guard
(GPG) as a "front-end" to supply the password to the disk-encryption.
The idea here is that the disk-encryption password is a long string
of random bits, that is itself encrypted by GPG. You may use GPG to
encrypt however you want: you may use public-key encryption, in which
case you may have a number of users, each with their own secret
password, all of them can decrypt the disk-encryption password and
thus access the loop-AES partition.
Please look carefully at the loop-AES README for those examples.
dd is rather risky, but using a 1GB partition as a staging area
sounds too difficult to do reliably; do it wrong, and its more risky
than dd (because of implementation or user error). I do large
transfers by simply mounting two different loop-AES disks, and using
cpio or star or rsync to copy subsets of data from one volume to the
other -- the userland tools are not aware of the underlying
encryption, and I can verify the integrity of the data before
deleting the older volume. I only do this sort of thing to migrate to
larger hard disks as they become available, and I always keep at
least two copies of my data, at least one copy is offline (cold disk
or tape).
~ boyd
Boyd Waters
Socorro, New Mexico
-
Linux-crypto: cryptography in and on the Linux system
Archive: http://mail.nl.linux.org/linux-crypto/
