[dm-crypt] (More) Questions about LUKS / LVM

Robbie Smith zoqaeski at gmail.com
Tue Sep 20 12:36:58 CEST 2011


Ah, that makes sense. It clicked with me after reading the paper on the
wiki. When you set up the system, it generates a random "master key",
which each key slot encrypts separately. So unlocking any key slot
unlocks the master key, which is then used to decrypt the disk. That's
rather clever actually.


At the moment I'm only planning to encrypt the onboard HDD of the
laptop, mainly to protect it against unauthorised access. It's a
brand-new machine, so I guess there won't be any noticeable latency with
an i3 or i5 processor. I had a few concerns as at the moment I'm using a
5+ year old Pentium "D" (P4 with hyperthreading?) and I get noticeable
latency with some applications; I didn't want to potentially add to
that.


What are some potential worst-case scenarios? i.e. the system had a hard
reset, either because the power got cut or (somehow) an application
brought the system to a complete halt? How would this affect the
encryption, and could it result in total data loss? 

The FAQ makes mention that the most frequent cause of data loss is
either losing access to the keys or somehow corrupting the LUKS header.
The former I can understand, and "common" sense would dictate to have a
couple of backup keys in secure locations. I am at a loss though as to
how someone could unintentionally corrupt the header though. 

I'm inclined to set up my system with /boot and a LUKS partition, and
then use LVM inside that, so if I decide to rearrange virtual partitions
I won't run the risk of messing up the LUKS header. This also seems like
the simplest setup.

(I keep daily backups of $HOME and of essential system settings, the
rest can be reinstalled if needed, but I'd prefer not to have to spend a
few days recovering everything if I had a hard reset or something like
that.)


Robbie



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