Bug#678015: debian-installer: Guided partitioning took 26 hours to complete erasure of encripted LVM volume

[Touko Korpela <touko.korpela@iki.fi>]

On Mon, Jun 18, 2012 at 09:54:13PM +0200, Philipp Kern wrote:
> On Mon, Jun 18, 2012 at 01:40:23PM -0300, Fernando J. Rodríguez wrote:
> > Please consider: a) changing the erase algorithm for someting more
> > expeditive, even at the expense of some effectiveness; b) asking the user if
> > she actually wants to erase the contents of the newly created volume; c)
> > warning the user that the erasing could take more than 1 day.
> 
> The latter probably makes sense.  I'm pretty sure that the user is asked,
> because I always skipped it.  On the other hand it's not for pre-existing data
> to be wiped but for the encrypted volume to appear completely random.
> Otherwise it's pretty obvious which blocks are allocated and which are not.
> (Not sure how useful that information is.)
> 
> It's not about effectiveness but about security, sadly.

If it is using /dev/urandom now, that is overkill.
There exists many algorithms/programs using random output (many packaged
in Debian) that are many times faster and they are safe enough for this.