[dm-crypt] loop file with partition problems

Arno Wagner arno at wagner.name
Wed Feb 29 17:40:31 CET 2012

On Wed, Feb 29, 2012 at 05:26:03PM +0100, Giovanni Di Stasi wrote:
> Hi everyone,
> I am having problems accessing a partition I have created on a file.
> I have never managed to mount it after reboot.
> I am using Debian (testing).
> This is what I did:
> # sudo -i
> # echo aes >> /etc/modules
> # echo dm_mod >> /etc/modules
> # echo dm_crypt >> /etc/modules
> # dd if=/dev/urandom of=.encrypted bs=1024 count=500000
> # sudo cryptsetup -y create crypt .encrypted
> # echo "crypt /home/giovanni/.encrypted none none" >> /etc/crypttab
> # sudo mkfs.ext4 /dev/mapper/crypt
> # mkdir /home/giovanni/cip
> # chown giovanni:giovanni /home/giovanni/cip/
> # sudo mount /dev/mapper/crypt /home/giovanni/cip
> # ls /home/giovanni/cip/
> # sudo umount /home/giovanni/cip
> # sudo mount /dev/mapper/crypt /home/giovanni/cip
> After rebooted, I don't really know how to mount my partition.
> I have tried this:
> # sudo -i
> # cryptsetup luksOpen .encrypted crypt
> Device /dev/loop0 is not a valid LUKS device.
> Did I lost all my data as I suspect? If so, why?

You are confusing plain dm-crypt and LUKS. You created the 
crypto-container (which is not a partition but a whole 
decive here) as plain dm-crypt and are trying to map it
as LUKS. These two are different and not compatible.

Try this:

 cryptsetup create crypt .encrypted
 mount /dev/mapper/crypt /home/giovanni/cip

Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno at wagner.name 
GnuPG:  ID: 1E25338F  FP: 0C30 5782 9D93 F785 E79C  0296 797F 6B50 1E25 338F
One of the painful things about our time is that those who feel certainty 
are stupid, and those with any imagination and understanding are filled 
with doubt and indecision. -- Bertrand Russell 

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