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"Smash Your Hard Drive" To Fight Identity Theft
Will Do This For Free writes "BBC News has a story about the only fireproof way of safeguarding your personal information when dumping your old computer: 'It sounds extreme, but the only way to be 100% safe is to smash your hard drive into smithereens. [...] The more thoroughly the better.'
This sounds like so much fun that I almost feel like doing it right now. Let me press Submit Story first."
His PC died due to dust accumulation (fried mobo, dead power supply, fused RAM) and he asked me what to do with his system. I told him the only thing he needed to worry about was his HD. Told him to drill a few holes in the drive, use a blowtorch in those holes if he still had one (he used to work in home remodeling), smash the drive with a hammer and put it in a bag with his used cat litter (they have two cats).
If someone is desperate enough to want the information on his drive, they're going to have to work for it.
We will bankrupt ourselves in the vain search for absolute security. -- Dwight D. Eisenhower
I periodically contract with a company to dispose of old hardware for my company. The first time i talked to them, they mentioned they shredded old media. I assumed he meant floppies and tapes and the like. Given the nature of the material, it didn't seem that impressive, but certainly nice. When I got the estimate, I was a bit shocked--why was it so high? Then they explained--by "media," they meant hard drives. They sent me a PDF on the equipment. Hard drives are removed from machines, and placed on a conveyor belt. This fed the hard drive into the shredder. On the other end, bits of metal came out. I begged them to let me operate it--just for one or two drives. Damn lawyers!
Throwing into fire is not enough, the magnetic domain on the platter is still there for highly technical team to retrieve. You have to melt the hard disk into liquid and stir thoroughly.
It is possible to reread some data from a zeroed (or oned (sp?)) disk. Pretty obscure, but I think it is to do with the threshold values of zero and one. For example, writing a location in sequence with 1,1,0 will result in a measurable [ though below threshold ] difference than if it had been 1,0,0. Seagate and the like do their best to squeeze this to the absolute minimum, thus maximizing utilization of the magnetic disc. I suspect it is much harder to recover anything meaningful from a 1TB platter than from a 5MB platter.
The other leak is with remapped sectors. Remapped sectors may contain live data, but have been switched out of use because they were unreliable. Flash has the same problem.
dd if=/dev/random of=/dev/sda takes care of the first problem - if you more paranoid than that, you should probably stop whatever it is you are doing.
You need a custom tool to access the remapped sectors.
The problem is that modern hard drives do automatic defect mapping. The end result is that sometimes important data can be written to a sector, and then the drive will decide that sector is unreliable and map it out. That sector can no longer be accessed in any way. As a result you have a sector which contains data but cannot be wiped because the drive won't let you write there.
Flash memory is even worse since it does write balancing between all cells to PREVENT a failure of a sector, rather than deciding a sector is on its way out and mapping around it then.
retrorocket.o not found, launch anyway?
About a decade ago, our artillery unit did do "rollovers" on hard drives for the intel unit. The drives, although already drilled through, were stored in a safe and ecsorted by Military Police. After we ran them over, the pieces went back into the safe. After the drilling and crushing, the drives were to be put into a 55 gallon barrel (along with wood or paper), doused in fuel, and burnt for a minimum of 30 minutes.