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Re: [dm-devel] my encryption



On Mon, Oct 20, 2003 at 06:58:36PM +0200, Erik Tews wrote:
> On Sun, Oct 19, 2003 at 09:56:45PM +0200, jon kollegiegaarden dk wrote:
> > > > > > It doesnt shuffle the sectors arround
> > > > > 
> > > > > Does this really provide more security ?
> > > > 
> > > > Maybe, i'm not a cryptoanalyser, but GBDE does this, and i think they
> > > > do it for a reason. The idea is that you can attack the encryption if
> > > > you have "known plaintext", and a filesystem stores known meta data
> > > > at a known location.
> > > 
> > > This is correct, I think this is a fine idea, if the blocks a big enough
> > > that this will not make the disk seek all the day.
> > 
> > i'm not aware of how big blocks that GBDE uses.
> 
> Usually, filesystems will try to save files with all sectors together in
> one line. If you use for example 512 byte blocks and shuffle them all
> over the disk, you will perhaps get less then 10% as usual while reading
> a file.
> 
> If you use 4 mb blocks like lvm does it (in old versions) you won't
> notice anything.

okay, but i still dont know what GBDE does.



JonB



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