[dm-crypt] password recovery for a luksOpened device?

Arno Wagner arno at wagner.name
Wed Nov 2 08:30:39 CET 2011

On Wed, Nov 02, 2011 at 08:23:33AM +0100, Milan Broz wrote:
> On 11/02/2011 04:14 AM, mike dentifrice wrote:
> > Or do I necessarily have to jump towards the "How do I recover the
> > master key from a mapped LUKS container?" FAQ entry?
> You can run that script mentioned there (it will generate master-key-file
> from active mapping).
> And then (instead of format) just run
> cryptsetup luksAddKey --master-key-file=<master-key-file> <luks device>

I thought so. Very good, added to the FAQ.

> and add new arbitrary passphrase.
> (If cryptsetup there doesn't support this option, you can do it on LUKS
> header clone outside of server and copy it back with new keyslot.)
> Without using dictionary or brute force attack you cannot recover original
> passphrase though.
> In any case, save "dmsetup table --showkeys" output, it will allow to map
> device even if you destroy LUKS header.
> Milan
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Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno at wagner.name 
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