LUKS Header crruption

Hi List,

as a result of executing a command from the history, after a reboot, when the disk letters were changed, I have accidentally overwritten the LUKS header with the raid superblock one :(

Now I can not open the cryptodisk with the "luksOpen" as it states the "No key available with this passphrase."

However, when I run "luksDump" the header information is available

# cryptsetup luksDump /dev/sdd1                                                                                                                                      
LUKS header information for /dev/sdd1

Version:        1
Cipher name:    aes
Cipher mode:    xts-plain64
Hash spec:      sha256
Payload offset: 4096
MK bits:        256
MK digest:      a6 a6 de 04 5a 19 9f 97 54 a9 79 bf f8 c1 37 89 69 44 34 76 
MK salt:        7a 0b 8e cc 68 06 35 ec 09 fc 5e f9 90 e3 c9 ef 
                8b 11 96 10 4c 25 ab 89 a1 48 df fe 6a 88 20 96 
MK iterations:  232809
UUID:           0f91c412-6f6a-405d-8040-5cc17ad17b47

Key Slot 0: ENABLED

        Iterations:             3724958
        Salt:                   c4 52 ac 04 59 8a d1 4f 7a 3c 5d e8 d3 50 1a c4 
                                11 20 0b 66 66 81 78 09 9f 7a f4 c1 dc 80 d4 40 
        Key material offset:    8
        AF stripes:             4000

Key Slot 1: DISABLED
Key Slot 2: DISABLED
Key Slot 3: DISABLED
Key Slot 4: DISABLED
Key Slot 5: DISABLED
Key Slot 6: DISABLED
Key Slot 7: DISABLED

The RAID superblock that was written by mdadm is default, version 1.2 that
is located 4K from the beginning of the device.

Providing that I have no backup of the original header and I know wht was written, is there a way to restore the header and get the data?

Konstantin
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Thanks Arno, thought so :(
Its a real pity that metadata is not redundant in luks v1.

Regards,
Konstantin

----- Original Message -----
From: "Arno Wagner" <[email protected]>
To: [email protected]
Sent: Sunday, 28 July, 2019 11:00:49 PM
Subject: Re: [dm-crypt] LUKS Header crruption

Hi Konstantin,

sorry, you data is gone. You overwrote the start of the first key-slot and there is no way to recover from that without backup.

One of the reasons why I think RAID superblocks at the start of the device (and even more so at 4kB offset) are messed up and a sign of clueless designers.

Regards,
Arno

The key material is quite deliberately made just the opposite of redundant. It is artificially inflated (typically 4000X) to occupy a larger area of the disk, and in such a manner that successfully erasing any portion of that area makes the key unrecoverable.