Every cop show has the tech boys in the lab restoring “wiped” hard drives. But let’s say the Feds are at my door and after my Moon Laser plans. I keep them on DVD and give each disc a couple solid whacks with a hammer, breaking it into 3-4 pieces. How likely is it that these can be restored and my plans retrieved?
What if they’re kept on a garden variety USB stick (nothing reinforced or a teddy bear with a USB plug) given the same hammer treatment? Are my plans safely destroyed then? How about a flash card?
Crap, I forgot I’ve been working on this Moon Laser since my Commodore 64 days. I pull the actual “disc” out of my 5.25" floppies and go over them several times with an X-Acto knife. Am I safe yet?
These are the Feds so assume they have the best technology money can buy.
For the floppy cut a few times with a knife, probably not. It’s a flexible magnetic media, and the data isn’t so densely packed, so in theory all you would need to do is fit the pieces back together and hold them in place with tape.
The DVD and USB stick are more problematic as they’re made of stiffer material which can shatter into tiny fragments.
The fastest way to render an unwanted hard drive unreadable is to break the platter inside with something like a hammer and nail. There are even special tools that work like a press or a giant nutcracker that large IT departments sometimes use to decommission sensitive hard drives. No one can recover any significant data from that. The same is true for a DVD. The DVD wouldn’t just break in a few pieces. It would also shatter along the edges on the break as well. Same idea and same result.
USB sticks are different. You could probably break a flimsy one for good with a hammer but it is harder to tell just by looking at it. The one I carry is ruggedized and would survive multiple hammer blows just fine. You would need to almost pulverize it to be sure although you could probably incinerate it fairly quickly as well. Cutting it in pieces with sheer would work as well as long as it isn’t ruggedized like mine.
This is one of those questions where those that talk don’t know, and those that know don’t talk.
In the case of the USB drive, it’s going to depend on whether the die of the flash memory chip itself is damaged. A few years back a friend of mine accidentally broke her thumb drive. The PCB was cracked, but the flash memory chip was undamaged. With some very careful soldering I was able to get it working again long enough to get the contents off. She was lucky that none of the pins had broken off the package. With better tools, it’s possible to open the memory chip package and make electrical connections directly to the chip die. If the actual silicon die itself is cracked or broken, it’s probably unrecoverable.
Use heat to destory magnetic media. Thermite to be sure.
The OP mentioned smashing a DVD. In my experience, they’re actually hard to smash, as they will flex quite a lot. But when one does break, usually the foil layer separates, so it’s going to be hard to reconstruct it. I’ve since started to use a shredder to destroy DVDs, and I don’t see how anyone could reconstruct them from the little chips that result.
Nuke the entire drive from orbit. It’s the only way to be sure.