[PLUG] Setting up encrypted file system

श्रीधर नारायण श्रीधर नारायण
Fri Dec 8 03:42:11 PST 2006


Hi all,

Answering query from a friend and in general reference for others and 
bots.. ;)

On Thursday 07 December 2006 16:56, you wrote:
> enc filesystem ???

Links:
http://www.linux.com/howtos/Cryptoloop-HOWTO/cryptoloop-introduction.shtml
http://www.saout.de/misc/dm-crypt/
http://www.gentoo.org/proj/en/hardened/disk-cryptography.xml

Steps:

Note that, in the dd step, zeroing the device is not secure enough. Ideally 
one should use /dev/urandom instead of /dev/zero but that would take couple 
of days to clear a 5-10GB partition with truely random data instead 5-10 
minutes for /dev/zero. 

An intermediate could be creating a file of 1-2M with /dev/urandom and 
overwriting the partition with that data. The actual commands are left as an 
exercise to the reader.

Of course replace the variables as required. And remember, these steps are 
highly destructive. Know before you do. You have been warned.

# modprobe cryptoloop
# time dd if=/dev/zero of=/dev/hdc7 bs=1M
# losetup -e blowfish /dev/loop0 /dev/hdc7
# mkfs -t ext2 /dev/loop0
# mount -t ext2 /dev/loop0 /mnt3
# umount /mnt3
# losetup -d /dev/loop0

Add following to /etc/fstab for permanent effect.
/dev/hdc7        /mnt3            ext2        users,noauto,encryption=blowfish               
1   0

HTH

 Shridhar



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