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These are some ways of disposing of hard drives: Special firms, degaussing, hammering, pulling apart.

Can this be accomplished more quickly by drowning it? Fill a bucket with water, maybe add some aggressive cleaning products, throw the drive in, let it sit overnight, then dump it in the garbage.

Will the data be irretrievable after that?

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Have you watched Prison Break? It might destroy the electronics, but I don't think it'll destroy the data. If you use acid, that's a different story. But the sure way is this: Open it, physically smash the disk/disks inside it. –  Adnan May 31 '13 at 6:49
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You could try waterboarding a harddrive for information... –  NULLZ May 31 '13 at 7:00
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Shredding and degaussing a drive both take about 10 seconds to do. Do you perhaps mean "cheaper" rather than "faster"? –  Graham Hill May 31 '13 at 10:47
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As implied by the joke made by @D3C4FF, Drowning implies loss of respiratory function. Dousing or dunking might be a bit more apt. The first time a hard drive drowns, I will be very concerned. –  JustinC May 31 '13 at 12:23
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Inventing your own data sanitation method is right up there with inventing your own encryption method. It might be fun to do but is not worth taking a chance on in a scenario that actually matters. –  stoj May 31 '13 at 16:46

6 Answers 6

up vote 31 down vote accepted

Special firms either degauss, destroy or melt the harddrives.

Harddrives are magnetic data. Magnetism can be destroyed by either:

  • Degaussing (changing the magnetism)

  • Heating the drive (melting) (which destroys/changes the magnetism)

  • Hammering (shock) (shock damages magnetism somewhat, but the denting of the drive makes it very difficult to read the surface, as metal deforms, the surface area changes as well thus making it even more difficult to determine what is and isn't a sector)

  • Drilling (removes sectors altogether, physically changes the layout of the drive like hammering, generates a large localised amount of heat as well)

  • shooting (same as hammering, but more extreme)

  • Chemical corrosion (if the magnetic substrate is removed from the platters altogether, there's nothing left to recover)

  • Shredding, there's plenty of services that offer to shred your harddrive which leaves you with nothing but metal scraps, nothing to recover there.

So, Would simply submerging the drive render it un-usable? No. Probably not to an experienced forensics or recovery team. What WILL kill the drive is corrosion of the platters, so it depends on what you add to the water, how long it stays in there, what the platters are made out of and how good the people trying to recover the data are.

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+1 For mentioning (the fun) ways in which one could destroy a hard drive in respect to OP's quesion. I know a single 7.62x54 round can make through at least 3 hard drives stacked together for efficiency. –  hydroparadise May 31 '13 at 14:49
    
Hydroparadise - for more fun, follow the link in my answer:-) –  Rory Alsop May 31 '13 at 15:18
    
Shooting works pretty good. I recommend a .223 –  Undo Jun 1 '13 at 0:41

No. Submerging a hard disk drive into water or any other non-corrosive liquid will do nothing to its platters that would render data recorded on them irretrievable.

It will most likely ruin hard drive's logic board (controller and other circuitry on its PCB), but that's not too hard to replace. Hard drive platters' magnetic recording surface is most commonly made of cobalt alloys, coated over aluminium alloy, or glass or ceramic substrate base. While water reacts quite good with pure aluminium, it wouldn't be used in its pure form for hard disk platter base, but would be either intentionally oxidized beforehand (thin oxidized layer protects aluminium remarkably well from further oxidation), or covered with a non-oxidizing material. The glass or ceramic substrate bases are obviously also not affected by water. So the answer to your question is - no.

One of more interesting and not too difficult ways to completely destroy any recorded data on the cobalt based recording surface however is by heating it over 1115 °C (its Curie temperature). This process, together with later cooling it down below 900°C will first reset materials magnetic field (realign magnetic spins, all reading either 1 or 0)1 and then cause antiferromagnetic ordering2, making any previously written data completelly irretrievable (read as interchanging 0s and 1s). This happens because cobalt oxidized to Co3O4 with heating it over Curie temperature, and then loses oxygen atoms with cooling below 900°C, ending up in CoO.

Above and below Curie temperature

1 Magnetism above (left) and just below (right) Curie temperature

Cobalt below 900°C

2 Antiferromagnetic ordering (cobalt below 900°C)

Anyway, just wanted to point out that it might not be necessary to completely melt the hard drive (cobalt's melting point is at 1495°C) to erase its data beyond being read back by any method. If this reads slightly geeky, don't worry about it, it is. ;)

EDIT: I was in such a geeky mode, I forgot to write how I usually deal with hard drives when I want to irretrievably destroy them. One method I find pretty easy is to saw them in half. It's pretty fun, and if someone still doubts they're damaged beyond use (it takes all kinds, I guess), you can slide a flathead screwdriver between hard drive's casing and the platter(s) and bang on it with a sledgehammer. That will crack its recording surface, possibly even all of it, including platter base. A bit of destructive fun there, that shouldn't be too difficult to achieve with a few common household tools.

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And that's why thermite works! :D Even if it doesn't melt through the drive casing (which especially in the cases of things like raptor drives happens a lot to me) the drive still ends up glowing red, so the disk is more than sufficiently heated :) –  NULLZ Jun 1 '13 at 1:09

As long as you open up the drive so your corrosive product can remove the magnetic coating from the platters then this should work.

It will, however, be much slower than the other mechanisms you mention, and will be harder to test for completion. Shredding is the fastest and easiest to confirm complete - it takes a few minutes and leaves you with dust.

We actually have a blog post and Question of the Week on this topic:

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Your best bet is thermite. Clive Robinson and I in discussions on Schneier's blog both agreed it's the safest, easiest method. It's partly easy b/c you can make it cheaply at home, legally in many areas, and safe b/c it take a magnesium rod to ignite. I couldn't find the full discussion for you so here it is in a nutshell:

  1. Take the drive apart gently or by smashing it. You want the platter and any chips (might have storage/cache).

  2. Put them in a kiln without stacking them.

  3. Put a layer of thermite on each object.

  4. Ignite it, close the kiln, and wait (far away).

The thermite burns hot enough to destroy the disks. The problem is the reaction is chaotic: it might not burn the precise points you want. The kiln contains the reaction, forming a superoven for electronic parts. The result is that the hard drive is destroyed. There's also a presentation by Skunkworks on an improved formula. That three of us independently came up with this solution and have used it turn hard drives into mush speaks to its effectiveness.

Note: The easiest way to erase a hard drive is to use full disk encryption with a very strong password. Then, you just have to erase the key and the data goes bye bye. If you're worried about being forced to give it up later, you can use a random long passphrase on a bit of cigarette paper and just burn it later. You can also use an inline media encryptor (see NSA IME) or, if you trust them, self-encrypting disks.

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No. Thermite is not your best bet. Thermite is a dangerous chemical reaction that can quickly get out of control if your not familiar with it. Shredding the drive is the safest and most efficient way of destroying multiple harddrives in my experience. –  NULLZ Jun 7 '13 at 1:48
    
I should add that i've used thermite on the raw platters in large quantities and have occasionally had issues with it not doing as much damage as expected... –  NULLZ Jun 7 '13 at 1:49
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@D3C4FF: When in doubt, use C4. –  Deer Hunter Jun 8 '13 at 19:07
    
For D3C4FF. You have to get the mixture right. Look up Skunkwork's thermite presentation for help in that regard. His was thorough and datacenter safe. ;) –  Nick P Jun 15 '13 at 20:46

Hard disks store information using magnetic disks. Water should will make the disk unusable by normal means as the electronics to control the disks would have been fried, however the disks themselves that contains the actual data will have a high chance of escaping unscathed and a "transplant" to a specialized equipment can still possibly recover the data. If you are really paranoid, open the hard disk and use a very powerful magnet (Powerful magnets can be found inside the hard disks as they are also needed to store data) to scratch the disks. The magnets should degauss the hard disk while the scratches should deal even more damage to the disk. Finally, either break the disks into pieces (Be careful - the newer disks may be made of glass even though they look like shiny metallic platters!) or burn and melt the disks.

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I like to take the drive apart. Use the magnets in them and apply the very strong magnet directly onto the platter in a swirling motion, then up and down and left to right. This should scramble all the data.

Check me on this.

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