Sinister quasi-governmental agencies succeeded in slipping a report into the public domain last week that claimed overwriting your hard disk just once was enough to protect it from any forensic data recovery.
The suspicion has always been that a magnetic force microscope could be used to probe overwritten sectors and extract the original data from the residual magnetic information at the edge of each track.
Well, this hired stooge apparently tried it, and it turns out that he was only able to recover 4 bytes of information nine times out of every million tries.
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While I'm prepared to accept that mounting a successful prosecution case on the strength of four incriminating bytes would be pretty hard, this completely overlooks the fact this "researcher" was using a regular, civilian-grade electron microscope.
What about the super-secret, perpetual-motion, dark matter, quantum cryptography microscopes that the government is hiding from us, eh? What about them? Against this sort of state-sponsored intrusion into your privacy the following data erasure protocol is recommended:
- Reformat disk
- Fill it with random data from the BBC home page
- Erase and repeat 17 times
- Remove disk drive from the PC
- Extract the disk platters
- Crush them with a jack hammer
- Mix the fragments with resin and cast it into a block
- Grind the block to dust and feed this to a beaver
- Toss the beaver into an active volcano
- Sever all connections with friends and family, have facial reconstruction surgery, change sex, move to Uraguay, take a vow of silence and throw yourself under a logging truck after leaving a forged suicide note.
Anything less is just taking unnecessary chances.