[dm-crypt] Restore a LUKS partition

[Michael Grosseck <liox@elso.mine.nu>]

Hello,

I created a luks partition for a long time with Ubuntu 10.04. Most 
likely I used following command to create it.

# cryptsetup -c blowfish-cbc-essiv:sha256 -y -s 256 luksFormat /dev/sda6

In the meantime I changed the distro to Linux Mint 13.
Now I tried to open it, but I get an error. Also if I try to dump the 
header information.

$ sudo cryptsetup luksDump -vc blowfish-cbc-essiv:sha256 /dev/sda6
Device /dev/sda6 is not a valid LUKS device.
Command failed with code 22: Device /dev/sda6 is not a valid LUKS device.

I was not sure if the drive is a LUKS device at all and I have read in 
another forum I should search for LUKS, what I did.

$ sudo dd if=/dev/sda6 | grep -a -b LUKS
0:�������?\x111�U�LUKS��\x01blowfishcbc-essiv:sha256sh 
E���\x17���֬�y[8�@��/�\x06ā\x04�]1b(�?K \x1c�uP�Xb6'\x18��C��
362478668:rC�+9���\\x01D�#�8*\x12tfoye�/�34ڛ�OCI\x1f[��\x19�5���E\x15!U�3_B\x02��%�\x11rLUKS�\x01$i}�H�[g>�rw̋��G�O 
�����6��>�b�\x02�s��e$�tɞV

So indeed it seems a LUKS device, but the header is somehow corrupt.

Now I tried to make a plain mapping what unexpected really works. But 
the joy was short. I can not mount the mapped device.

$ sudo cryptsetup create -c blowfish-cbc-essiv:sha256 -s 256 crypt /dev/sda6
Enter passphrase:
$ sudo mount /dev/mapper/crypt /home/crypt/
mount: you must specify the filesystem type
$ sudo mount -t ext3 /dev/mapper/crypt /home/crypt/
mount: wrong fs type, bad option, bad superblock on /dev/mapper/crypt,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail or so

Now my question. Is there a little hope to restore the LUKS header or at 
least to read the content of this partition somehow?

Thanks for your help

Michael