[dm-crypt] The future of disk encryption with LUKS2

Sven Eschenberg sven at whgl.uni-frankfurt.de
Mon Feb 8 21:51:34 CET 2016



Am 08.02.2016 um 21:31 schrieb f-dm-c at media.mit.edu:
>      > Date: Mon, 8 Feb 2016 17:41:43 +0100
>      > From: Arno Wagner <arno at wagner.name>
>
>      > The thing is that in a typical PC, power drops relatively
>      > slowly and disks work non-seeking for a lower voltage
>      > that the thresholds. Add to that that a single sector
>      > write takes less than 1ms (probably much less), and
>      > you get ample time to finish a write in progress.
>
> If the data has already made it all the way into the drive itself,
> that may be valid, but it's very dangerous to make such assumptions
> in general, and you can't necessarily know the timing of the power
> failure vs when the data makes it to the disk, much less the platters.

If the data hasn't made it to the drive (or rather is not in transit) 
then the change is just discarded leaving us in a stable state.
>
> http://zork.net/~nick/mail/why-reiserfs-is-teh-sukc
>
> And new technologies may change this---not just SSDs, but modern
> high-capacity drives that must rewrite many, many sectors to write
> one.  (Yes, I know this also argues that those headers should be
> far away from each other.  So be it.  If such scattered headers
> don't prevent resizing, I don't care.  Except maybe for secure wipe.)

Well, if we talk about SMR, small changes will be written to the random 
IO section of the drive and merged later. With those drives you'll 
probably never know if there's parts of the old header lingering around 
someplace else.

Regards

-Sven


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