Re: [dm-crypt] volume unrecognized

From: Moji <lordmoji@gmail.com>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] volume unrecognized
Date: Thu, 27 Aug 2009 10:45:30 -0500	[thread overview]
Message-ID: <4A96AA1A.9000901@gmail.com> (raw)
In-Reply-To: <d364213cb547d7748d391aad1f9d0422.squirrel@webmail.kapps.fr>

J.O.,

If all Ubuntu was did was rewrite the luks header information and you
have backups of the luks header, you can restore it.

As long as it was the original key.

-MJ

Jacques-Olivier KAPPS wrote:
> <quote who="Jonas Meurer">
>> hey,
>>
>> On 27/08/2009 Jacques-Olivier KAPPS wrote:
>>> I have a single encrypted partition which contains my data, /home. I
>>> just
>>> installed a new system (ubuntu karmic/alternate cd) over my other clear
>>> system partitions, and I tried to use the setup program to point my
>>> /home
>>> directory to my existing and crypted /home partition. Though, it
>>> eventually wanted to format it and I canceled the whole operation.
>>>
>>> Now I can map the device with luksOpen, but the volume itself is
>>> unrecognized.
>>>
>>> I certainly can open the device with luksOpen because I choosed the same
>>> password in the installation process, but my guess is that the ubuntu
>>> installer erased and replaced the luks headers of my partition by new
>>> ones, what do you think? Or maybe is just erased the table partition
>>> headers and it can't recognized the filesystem?
>> according to your description, you entered a new luks passphrase for the
>> encrypted device at ubuntu installation, right? to my knowledge ubuntu
>> installation doesn't support management of existing encrypted devices
>> yet. for that reason i fear that you reformatted the device (luksFormat)
>> during installation process. i hope that you do have backups in that
>> case as your data will be lost.
>>
>> even using the same passphrase doesn't help. the passphrase is only used
>> to decrypt the luks masterkey, and that masterkey is generated from
>> random data at luksFormat.
>>
>> please keep in mind that encrypted storage devices don't have backdoors
>> implemented. if the masterkey is destroyed/overwritten, the data is
>> irrevocably lost by design.
>>
>> you really should do regular backups of sensitive data, and even more so
>> if the data is stored on encrypted devices!
>>
>> greetings,
>>  jonas
>>
> 
> Thanks for the explanation,
> 
> My bad! I assumed that the ubuntu installer would open the existing
> encrypted device, and I didn't think anything was permanently done before
> the final "Are you sure you want format those partitions?".
> 
> Luckily I have some backups, but not really up to date. I am going to miss
> my summer photo shots!
> 
> regards,
> 
> J.O.
> 
> 
> 
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