[ale] really really deleting files....

[tfreeman at intel.digichem.net]

On 24 Jun 2003, James P. Kinney III wrote:

> On Tue, 2003-06-24 at 15:52, Keith R. Watson wrote:
> > At 01:34 PM 6/24/2003 -0400, you wrote:
> > >On Tue, 24 Jun 2003, Keith R. Watson wrote:
> > >
> > ><<snip>>
> > > > Recoverable - 1. Your data can't be reassembled and viewed by an 
> > > un-authorized
> > > >                   party regardless of the level of effort required (The NSA
> > > >                   couldn't do it with unlimited funds)
> > > >
> > >
<<snip>>
> A better (ahem) solution might be to use HCl. The platter surface is
> Ferrous Oxide known to most normal humans as rust. Hydrochloric acid is
> a very effective rust remover. As the casing metal is usually aluminum,
> the acid will work itself to death converting the aluminum to AlCl, a
> harmless salt.
A nit, but that would be AlCl3. 

For an aluminum platter, that might be a good idea too. With the current 
platters being glass, I suspect that HF would pit/erode enough of the 
surface that even if a section of the platter could be recovered, surface 
defects would be amazingly challenging to the AfM instruments.

What I'm not sure about is the effect of HF on either Fe2O3 (or the other 
oxides) or aluminum. My understanding is that AL metal tends to form a 
surface scale which will tend to protect the bare metal for a time.

> 
> I don't think it would be possible to reassemble the dissolved FeO2 and
> recover any magnetic domains.
> 
> But the issue as posed is more "How to securely recycle a hard drive".
> 
> My (untested) solution (using no caustic chemicals):
> 
> For i in 0 1 2 3 4 5 6 7 8 9 do
> startblock=$(9-$i)
> dd if=/dev/random of=<ramdisk>/block bs=1048576 count=1
> dd if=<ramdisk>/block of=/dev/hdx obs=1 ibs=3 seek=$i skip=$startblock
> done
> 
> This would take a while with a 200G hard drive :)
> > 
> > -------------
> > 
> > Keith R. Watson                        GTRI/ITD
> > Systems Support Specialist III         Georgia Tech Research Institute
> > keith.watson at gtri.gatech.edu           Atlanta, GA  30332-0816
> > 404-894-0836
> > 
> > _______________________________________________
> > Ale mailing list
> > Ale at ale.org
> > http://www.ale.org/mailman/listinfo/ale
> 

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