Aah, yes, but you put hidden encrypted file in an encrypted hard drive, that's like 2 layers deep, just give them your password then. data still safe.
Or a hammer, screwdriver and strong magnet do the trick perfectly. Add some fire for show as well.
I always firgured the best bet would be to mix up some thermite, set it in a flower pot in the bay above the HD, put the pot base beneath the HD to catch the melted remnants, and rig up a magnesium ignition device. Instant liquid hard drive!
I'm not an expert on this matter, but a friend who happens to be an IT-guy told me that some types of HD-encrypting software allows you to set an alternative password, which, when you enter it, won't give access to the real, encrypted data on your HD, but to an alternative section/partition that you may set up.
I've seen a lot of discussions about the multiple layer approach and programs that hide encrypted partitions/files. The way I understand it, If there's an encrypted file, they'll demand the key, if they find evidence of a missing/inaccessible file or partition, they'll demand that key too.
So the only way to pull this off would be to trick any partition/disk analyzer they use into thinking an area of the HD is blank, and then covering any digital tracks within the computer referencing this area. For instance, you cant tell the OS not to write files to specific sectors of the HD, cause this is a giveaway. Having a 3 GB encrypted file, then opening it to show 2 GB will also point to an alternate encrypted file.
"I forgot the password" wont really work either:
http://www.wired.com/threatlevel/2012/02/laptop-decryption-appeal-rejected/The rumour is that apparently they can, you need to over write it at least 3 times. But that is only with that super duper secret government software.
From what I've read, with modern HDD's (let's say >100 GB) the data density is so high that overwriting once should be enough. Apparently, back when the disk of same size only held 100 MB, this was easier. Recovery after physical damage (fire etc.) is also becoming more difficult due to this.
Ah this is interesting. I've always heard it took at least a few wipes, plus extra for government type stuff. But then, many military computers are using what we would consider very outdated hardware, so I wouldnt be surprised if some disks were still in the 100 MB range.