[dm-crypt] Debian Boot

Yves-Alexis Perez corsac at corsac.net
Thu Oct 25 10:07:13 CEST 2012

On mer., 2012-10-24 at 18:33 +0200, Arno Wagner wrote:
> On Wed, Oct 24, 2012 at 04:05:34PM +0000, St?phane Bailleul wrote:
> > 
> > 
> > Hi  My PC just crashed, the hard drive were encrypted ( I don't exactly
> > know the method) but it was during the debian squeeze 64 bits
> > installation, one of the optionMy Hard drive with a separate / and Home
> > /dev/sda1 was the //dev/sda5 was the home it seems that something went
> > very bad on this computer, after turning it on nothing shows on the screen
> > after the bios.Using the rescue option on my CD, I have been able to mount
> > SDA1, I was trying to mount SDA5 but can notusing cryptsetup luksOpen is
> > says that it is not a valid device there is no mapper in /sda1/dev Is
> > there a way to mount sda5 and unencrypt the data ?I still have the
> > password I hope there is a solution CheersStephane
> Ok, lets start with the advice for this situation from 
> the FAQ: First, calm down.
> Some questions:
> 1.What exactly did you do? 
> 2. Did you install squeeze 64bit over some other installation 
>    you had before? What kind of other installation was that?
> 3. What was encrypted before and how? You seems to think sda5 was
>    encrypted with LUKS, why do you think that? (What do you
>    know about it that tells you it was encrypted?) 

Few precisions on Debian installer use of encryption. The “default”
encrypted setup is done using LVM, as:

/dev/sda1 → /boot
/dev/sda5 (logical partition, even though there's still room for other
primary ones) → luks partition (using, afair, aes-essiv but I'm not
completely sure) mapped as /dev/mapper/sda5_crypt
/dev/mapper/sda5_crypt is a physical volume for LVM on top of which are
a volume group (name from the hostname) and logical volumes
(for /, /home and swap)

So, in theory, cryptsetup luksDump /dev/sda5 should return the header
for the encrypted partition.


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