Re: how to sweep hard disk of confidential data
On Sun, Jul 18, 2004 at 08:59:38PM -0400, Silvan wrote:
> On Sunday 18 July 2004 06:52 pm, Doug Holland wrote:
>
> > If the answer is yes (usually we're talking about government contractors
> > with classified data), then the only answer is to physically destroy the
> > hard disk's platters.
>
> Yeah, and I guess at that you'd have to *really* destroy the platters.
> Cutting a hard drive in half with a bandsaw is fun, but it sounds like these
> guys might be able to recover something from it even at that.
>
> I guess you'd have to melt it down.
>
Probably not. You only have to heat the platter to a temperature above
the Curie point of the ferromagnetic material that coats the
platter. This is usually a few hundred degrees C below the melting
point. The information is stored in the remanent magnetization of the
coating on the platter. Above the its Curie point, the material
becomes paramagnetic and is incapable of retaining remanent
magnetization and therefore incapable of storing information.
But this is a temperature well above what is necessary to turn all the
plastic parts of the disk drive into noxious vapor.
--
Paul E Condon
pecondon@mesanetworks.net
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