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Posted by mike3 on November 25, 2004, 6:22 pm
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Hi.
Would this make a good mechanism to securely destroy a hard drive?
1. Crash the heads into the platters with the drive at top speed
2. Seek them from one edge of the platters to the other back and forth
to \
ensure good grinding
3. Pump a concentrated hydrogen/oxygen mix into the hard drive platter
chamber
while the heads are grinding away.
Would the heat from the grinding be enough to ignite the H2/O2 mix and
ensure that data can't be recovered? Would this mechanism be good
enough to keep copies of a large company's trade secrets from a
competing large company?
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Posted by Walter Roberson on November 26, 2004, 3:46 am
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:Would this make a good mechanism to securely destroy a hard drive?
:1. Crash the heads into the platters with the drive at top speed
Without opening the drive to do so? You'd have to subject them to
a shock in excess of 25g's: drives aren't sensitive beasts anymore.
:2. Seek them from one edge of the platters to the other back and forth
:to \
: ensure good grinding
You'd have to -keep- the heads on the platters while you did that.
Might be a bit tricky if the drive heads essentially float on a
Bernoulli Effect or diamagnetic levitation rather than being
mechanically positioned. Keep in mind too that a modern drive is
multiple platters with heads on both sides of the platters: you can't
count on gravity to keep the heads grinding against the platters.
:3. Pump a concentrated hydrogen/oxygen mix into the hard drive platter
:chamber
: while the heads are grinding away.
:Would the heat from the grinding be enough to ignite the H2/O2 mix
http://www.hydrogensafety.info/articles/04-feb-04.asp
indicates that "hydrogen is a group B gas with an auto-ignition temperature
of 520C to 585C depending on the information source".
In a table slightly further down, it indicates that the flame temperature
is 2318 Kelvin (fairly similar to propane.) That is provided, of course,
that one is burning the hydrogen rather than exploding it. To burn
the hydrogen, the concentration "in air" must be between 4.0% and 18%,
or else 59% and 75%.
:and
:ensure that data can't be recovered? Would this mechanism be good
:enough to keep copies of a large company's trade secrets from a
:competing large company?
Well, 2318 K is well above the Curie temperature of Iron (1043 K)
and -way- above the Curie temperature of Neodymium magnets (320 C)
http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/neodym.html
Thus if you could keep the hydrogen burning instead of exploding, you
could do a dandy job of weakening the magnetism of the recorded information.
You'd have to be careful, though, because ferrous materials become
paramagnetic above their Curie temperature. For best effect, you should
probably put the whole thing in a large magnetic field so as to realign
the platters before recooling below the Curie temperature.
Still, I somehow can't help feeling that your proposal would -somehow-
be unsatisfactory in protecting trade secrets when there is a large
amount of money at stake. I would suggest that the company hire one of
the military-grade disk destruction specialists, which usually involves
physically grinding the drive into tiny pieces.
--
I predict that you will not trust this prediction.
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Posted by Doug McIntyre on November 26, 2004, 4:33 am
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>Would this make a good mechanism to securely destroy a hard drive?
>1. Crash the heads into the platters with the drive at top speed
>2. Seek them from one edge of the platters to the other back and forth
>to \
> ensure good grinding
>3. Pump a concentrated hydrogen/oxygen mix into the hard drive platter
>chamber
> while the heads are grinding away.
>Would the heat from the grinding be enough to ignite the H2/O2 mix and
>ensure that data can't be recovered? Would this mechanism be good
>enough to keep copies of a large company's trade secrets from a
>competing large company?
Sounds like way more specialized work than just taking the platters
out and burning them, or running a grinder over the platters scrapping
all the iron oxide off them or chipping the platters into a billion
tiny parts. Simple is almost always best.
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Posted by Al Dykes on November 26, 2004, 12:37 pm
If you were Registered and logged in, you could reply and use other advanced thread options >Hi.
>
>Would this make a good mechanism to securely destroy a hard drive?
>
>1. Crash the heads into the platters with the drive at top speed
>
>2. Seek them from one edge of the platters to the other back and forth
>to \
> ensure good grinding
>
>3. Pump a concentrated hydrogen/oxygen mix into the hard drive platter
>chamber
> while the heads are grinding away.
>
>Would the heat from the grinding be enough to ignite the H2/O2 mix and
>ensure that data can't be recovered? Would this mechanism be good
>enough to keep copies of a large company's trade secrets from a
>competing large company?
A concrete floor and a 5 pound sledge hammer.
Anyone that claims to be able to read data from a disk platter
that isn't flat and balanced needs to give me something
to back up that claim.
--
a d y k e s @ p a n i x . c o m
----
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Posted by Moe Trin on November 26, 2004, 4:30 pm
If you were Registered and logged in, you could reply and use other advanced thread options
>Would this make a good mechanism to securely destroy a hard drive?
>
>1. Crash the heads into the platters with the drive at top speed
Modern (since the early 1990s) hard drives have a very hard and smooth
surface on the platters. Crashes do occur in real life, and normally
cause no harm. "Top speed" implies the disk powered up and running
normally (heads NOT parked). How do you propose to cause the 50+Gs to
crash the heads while in this condition? Hard drives have gotten a lot
more resilient since Reynold Johnson's "baloney slicer" system in 1956.
>2. Seek them from one edge of the platters to the other back and forth
>to \
> ensure good grinding
See above. Every time you power down a drive, you "crash" the heads
(admittedly at a slower speed) - how much damage to the heads does that
cause? To the media?
>3. Pump a concentrated hydrogen/oxygen mix into the hard drive platter
>chamber
> while the heads are grinding away.
If you are going to be cracking the case (airflow through the vent is
meant to equalize pressures, not cause an air exchange), why not open
it up the rest of the way, and yank the platters so that you can put
them directly in a fire and melt them.
>Would the heat from the grinding be enough to ignite the H2/O2 mix and
>ensure that data can't be recovered?
No. Not enough energy in the H2/O2 that would remain in a typical hard
disk without exploding and blowing open the case. Such an explosion
might damage the drive to make it unusable, but wouldn't damage the media
enough to preclude data recovery.
>Would this mechanism be good enough to keep copies of a large company's
>trade secrets from a competing large company?
No.
1. Go find a recent copy of a hardware book such as Scott Mueller's
"Upgrading and Repairing PCs" from Que, Roche's "Hardware Bible", and
learn about hard disk construction.
2. http://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html for a
classic paper on removing information from computer disks.
Old guy
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