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Date: Wed, 04 May 2011 08:11:21 +0200
From: Milan Broz <mbroz@redhat.com>
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Subject: Re: [dm-crypt] extracting master key from luks header, cryptsetup
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To: anirudh <anirudh.takkallapally@gmail.com>
Cc: dm-crypt@saout.de

On 05/03/2011 10:50 PM, anirudh wrote:
> Is there a way to extract the master key from luks header if we have the key or
> pass-phrase used to encrypt the volume using cryptsetup?

If you want to really backup master key (and not the whole header with known
keyslot with luksHeaderBackup) use "luksDump --dump-master-key" command
(available in cryptsetup 1.2.0, passphrase for some keyslot is required).

(Also you can activate device and save the mapping table with master key
with "dmsetup table --showkeys <active device>".)

Milan