Hi

Using losetup you can set a loop device for a particular partition and it will ask
passwords for the same. After this one can mount that loop device to a some
mount point. If the password is not correct, the mount will fail.
For eg:

[root@root]# losetup  -e xor /dev/loop3 /dev/hda2
Password:
[root@root]# mkfs -t ext2 /dev/loop3 100
[root@root]# mount /dev/loop3 /NETBSD/
[root@root]# ls /NETBSD/
lost+found
[root@root]# echo hello > /NETBSD/hello
[root@root]# cat /NETBSD/hello
hello
[root@root]# umount /dev/loop3
[root@root]# losetup -d /dev/loop3

Checking if the partition is encrypted
-------------------------------------------------------
[root@root]# mount /dev/hda2 /NETBSD/
mount: you must specify the filesystem type

Mouting it using password
--------------------------------------
[root@root]# losetup  -e xor /dev/loop3 /dev/hda2
Password:
[root@root]# mount /dev/loop3 /NETBSD/
[root@root]# ls /NETBSD/
hello  lost+found

But after mounting the partitiion, it doesn't provide any security and the files will
be accessible by everyone who has the right to access it. The protection is that it
will ask for passwords when mounting that partition, so if somebody steals
the computer after a power-off, he will not be able to mount and see the files under
the encrypted partition.

Regards

Suneesh


Lei Yang wrote:
Hello,

I am trying to play around loopback device and want to set up an
encrypted loopback filesystem. I did the following things:

1. losetup -e serpent /dev/loop0 /etc/crypt
/ect/crypt: Is a directory

So I tried: losetup -e serpent /dev/loop0 /etc/cryptfile and this time
cryptfile is a plain txt file.

Enter passwd...

2. mkfs -t ext2 /dev/loop0
3. mount -t ext2 /dev/loop0 /mnt/crypt

After this, how do I verify that anything happened that has enabled
encryption? I can't understand where the encrypted filesystem lies in
here:( Plus, when we say 'encrypted', which file is on earth encrypted?
Is that files and data in /mnt/crypt are encrypted form of
/etc/cryptfile? Really confused.

TIA!

Lei 


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-- 
Suneesh T P,
Senior Associate, Embedded,
NatureSoft Pvt Ltd.
Mailto: suneesh@naturesoft.net
WebSite: www.nature-soft.com