shredding files on a flash drive

[Kristian Erik Hermansen]

On Jan 26, 2008 12:48 PM, Peter P. <plpeter2006-/E1597aS9LQAvxtiuMwx3w at public.gmane.org> wrote:
> There exists software and there are systems that are able to stitch back
> together essentially documents torn to confetti and read what was on them. They
> are used by archaeologists among others. The original application was to stitch
> back together old documents (even with missing parts!) and tapestries. At least
> one application is open source, and serves to digitize old 8 and 16 mm films
> using a flatbed scanner. The software stitches the succesive exposures of
> several frames each together, picking them out of the background and the film
> frame, and makes a modern computer movie from them.

Yes, and I have written my own Artificial Intelligence
algorithms/software that does this.  Have you?

> All modern tape and disk drives do not use alignment between the platters for
> any special purpose. Each head has its own data channel. Not working like that
> would require the platters and the heads not to have any vibration (including
> rotational) to the tune of one half a bit space on the disk. That would be in
> the few tens of nanometers at most today. Move this to four or six faces to keep
> in sync and a price tag usually well below $300 and you have a picture of
> something that cannot be done. $300 won't buy you the motor and control system
> that guarantees rotational noise below say 50 nanometers at 7200 rpm no matter
> what. Compare to video recording where the heads move against the tape with
> something like 2 m/sec and rotational vibration effects are of the order of
> magnitude of 10 usec per head rotation at a bandwidth of only 1.5 MHz when all
> is well (rarely). A hard disk head channel will have something like 10-20 m/sec
> head speed (7200 rpm) and probably 10-100MHz bandwidth.
>
> Any instrument maker will tell you that such things do not work outside a lab.
> Tapes have the same problem (longitudinal skew and warping) and deal with it the
> same way: each head has its own data channel, clock and data recovery state
> machine (including ML masking/decoding), and mini buffer. This has been true
> since at least the 1970s when 7, 8 and 9-track tapes ruled the world. Also most
> normal hard disks do not stripe the heads and use one head at any one time. Only
> high end drives stripe the platters and use all the heads together (but still
> with each having its own decoder and mini buffer).
>
> Also there will always be files with known data on the remains (at least sector
> headers) that will allow the interleave assembly scheme to be divined. Now add
> 1+1 together with the confetti assembler above and you have a working recovery
> system. Yes, it would take a few weeks of hard work at least. Yes, there are
> people who would do such things to get at other countries or companies goodies.
> Consider that at current data densities a 1mm length of track could allow the
> recovery of 10 kilobytes of data. How many names and addresses or social
> security numbers can be stored in 10 kilobytes ?
>
> Imho it is pretty lame to 'make your point' by quoting a paper written by
> (knowledgeable) people relatively out of context when there are tons of counter
> examples on the net. Sorry for writing this. Add to this that if I know this as
> a 'civilian' who is not in the security field at all, there must be people who
> know A LOT more. And no, I did not 'prove my point'. I just brought some
> arguments into the discussion. This is not a pissing contest as far as I know.

If you are indeed correct, I would like to inform you that the
Department of Homeland Security of the United States has offered a lot
of money to anyone who can product such a "magic device" that can
perform the actions you say.  It sounds like you will be very rich,
very soon :-)
-- 
Kristian Erik Hermansen
"Know something about everything and everything about something."
--
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