On 6/1/05, Diana Eichert <[EMAIL PROTECTED]> wrote: > On Thu, 2 Jun 2005, Dennis Lindahl wrote: > SNIP > > Like I said, once the information _has_ been overwritten, it cannot be > > recovered in any lab. A fellow from IBAS said this during a seminar I > > attended recently. He even said it was a fundamental principle for all > > professional data recovery. If it had been possible to retrieve > > overwritten data from harddisks, im pretty sure the technique would have > > been used in some high profile criminal investigation. But it hasnt, > > because it is a myth. > > > > And like you said, there are indeed issues to actually performing a > > complete overwrite. > > > > / Dennis > > > > Let me 'splain something to you in PLAIN English. The US Gov't is WILLING > to RELEASE and NOT PROSECUTE spies if it appears that CLASSIFIED > information COULD be compromised in a court trial, NOT will be > compromised, just the CHANCE of it occurring. Therefore just because > YOU haven't heard of a way to recover over written data doesn't mean it > can't be done. > > FWIW I don't personally know of a way to recover over written media, what > I can say is that media is physically destroyed at various facilities I've > worked at. > > diana > >
>From my understanding of it, the values stored on your harddrive are not exactly one's and zeros. As long as the magnetic field is close to zero, like .15 gauss (or whatever the unit would be), it is treated like a zero. If it is close to a one (like .83 gauss, again I'm not sure what the value or unit would actually look like) it will be regarded as a one. By analyzing these true values of the magnetic field, professionals can infer what that particular bit used to be.
