[no subject]

On 6/9/05, Greg Freemyer <greg.freemyer at gmail.com> wrote:
> 
> On 6/8/05, Michael B. Trausch wrote:
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> > Hash: RIPEMD160
> >
> > tfreeman at intel.digichem.net wrote:
> > >
> > > About 10 years or more ago, I used one of those drive recovery 
> services.
> > > Yes, expensive, but not all that expensive. Seems like we had a 
> discusion
> > > of sorts along the lines of secure deletion a year or two ago. I 
> _still_
> > > like the idea of floating the platters in HF, although there are
> > > hazzardous waste issues.
> > >
> >
> > Many of the drive recovery services are capable of much more then you or
> > I can do with any disk or disk controller available to us within any
> > sort of reasonable cost range. For example, some services can read data
> > that was written and overwritten, and overwritten yet again, by looking
> > for "ghosts" of data and reassembling it. Crazy, but (remotely) 
> possible.
> 
> The "ghosts" are called "fringe effects". Ones and Zeros on a disk
> have physical dimension and I assume the strength of the magnetism
> fails off in a gausian curve (Think back to advanced physics class).
> Head alignment is not perfect, so over-writes do not exactly
> over-write, but instead the center of the curve is slightly offset.
> As you say a highly calibrated and sensitive head assembly can in
> theory read the field strength of the magnetism with a far greater
> accuracy than just 1/0.
> 
> Then very complex software can "in theory" reassemble the underlying data.
> 
> I am not aware of any commercial provider offering that they can read
> "fringe effects".
> 
> I'd be very interested to know of a commercial service provider that
> can actually do that.
> 
> I've heard the rumors that CIA / NSA / etc. can do this and I have
> little reason to doubt it, but I imagine they can only get little
> fragments of data, not full recovery.
> 
> FYI: The biggest support for this capability existing is the DOD
> wiping requirement that requires multiple passes. If technology does
> not exist to read data after a single over-write, then the DOD
> requirement is overly strict.
> 
> Greg
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<li><strong><a name="00388" href="msg00388.html">[ale] Drive recovery</a></strong>
<ul><li><em>From:</em> tfreeman at intel.digichem.net (tfreeman at intel.digichem.net)</li></ul></li>
<li><strong><a name="00389" href="msg00389.html">[ale] Drive recovery</a></strong>
<ul><li><em>From:</em> fd0man at gmail.com (Michael B. Trausch)</li></ul></li>
<li><strong><a name="00411" href="msg00411.html">[ale] Drive recovery</a></strong>
<ul><li><em>From:</em> greg.freemyer at gmail.com (Greg Freemyer)</li></ul></li>
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