cool. Yeah, I'm assuming whoever wants the drive is prepared to use electron microscopes and such to uncover the bits on the mangled wreckage. So the question i

cool. Yeah, I'm assuming whoever wants the drive is prepared to use electron microscopes and such to uncover the bits on the mangled wreckage. So the question isn't just a informational entropy question, but a physical entropy question. How much physical entropy does Gutmann 35 pass (or n passes) add to the disk? Basically, somebody asked a listserv what was the best way to securely wipe a hard drive. I said Gutmann 35 pass, and others came back with ideas for thermite, shooting it, etc. I figured, compared to Gutmann, thermite (the most exothermic chemical reaction, and one that happens to use iron) would be the closest. But I got to thinking, you know, if that thermite just blasts, then you've still got fragments and Gutmann wins. If it's a smoldering sort of thing and you have plenty of oxygen, maybe thermite wins, but how much thermite would you need, and how would you have to do it? So I guess a better question would be what's the minimum necessary chemical reaction to equal the entropy of a 35 pass Gutmann?