Re: [dm-crypt] LUKS password forgoten, any way how to change it?

[Heinz Diehl <htd@fancy-poultry.org>]

On 06.03.2010, Marek Stopka wrote: 

> Hi guys, I have forgotten password to my luks encrypted disk, I have
> lost no data (yet :) ), because system is still running with unlocked
> device, but problem is, that I have a scheduled hardware maintanance
> window quite soon, so I was wondering is it somehow easily possible to
> luksAddKey without knowing a password or recover password from memory

No way. Do a complete backup of your existing data now, and you'll be able to
recover your encrypted partition after a reformatting later.

> or it will be much more easier to copy those data somewhere else and
> create a new encrypted disk? It is like 12TB of data so I would really
> prefer not to copy those data somewhere else, but if I will have to, I
> can pull that off...

Without the correct passphrase, and without any hackish memory manipulation
and similar, the only way is to copy your data to a safe place and to 
recreate your encrypted device later. To unlock/decrypt the master key,
you have to provide the correct passphrase first.
 
> But I am wondering since key need to be in a memory somewhere there
> could be a way... :)

You can read here how it works:

http://cryptsetup.googlecode.com/svn-history/r42/wiki/LUKS-standard/on-disk-format.pdf