Security
A friend of mine recently asked about a way to format a hard drive in such a way that “noone would be able to retrieve the information with any special tools.”
The problem with security is that, depending on your level of paranoia, no method is safe.
The CIA-approved methods of destroying disk data include pulverizing the hard disk platters and then burning them. Even then it is hypothetically possible to recover data from burned chunks of hard drive media, if the recovering organization has enough resources and the will to do so. For example, if you’re concerned about the Illuminati recovering your info, chances are they already have it, or they’ll use their super secret MKULTRA mind assassins to haunt your house and capture your data with spirit familiars.
I had a friend who went on a security paranoia kick a while back, and was all concerned over TEMPEST monitoring of his equipment. He was gonna build a Faraday-cage to shield all of his stuff, etc. Finally I told him, “Look, stupid, for one, you’re just not that important. You don’t do anything the spooks might be interested in. They’re not gonna park a van across the street just to watch you beat off to manporn. Furthermore, even if they decided to watch you beat off to manporn, they’d never use TEMPEST to do it. They’d break into your place when you weren’t home, and put cameras all over your house, and you’d never know.”