[jessaustin]

This isn't a panacea. Check out what the dm-crypt folks have to say about it (question 5.2):

https://code.google.com/p/cryptsetup/wiki/FrequentlyAskedQue...

tl;dr: even if your adversary can't "prove" you have another encrypted volume, when they can see all the random data on your disk or inside the "outer" volume, you can't prove you don't have an "inner" one. In a situation shitty enough that you're compelled to divulge incriminating secrets, you're boned whether you have another secret volume or not. Elsewhere in the FAQ they propose zeroing out unused space on your disk whenever travelling to totalitarian states that could demand decryption keys.

[danudey]

> they propose zeroing out unused space on your disk whenever travelling to totalitarian states that could demand decryption keys.

Like the UK: http://arstechnica.com/tech-policy/2007/10/uk-can-now-demand...

[dzhiurgis]

Wait a minute.

If I zero out drive using traditional method - data is still recoverable.

If I zero out drive using random data - I can be suspect and/or get free rubber hose for life, trying to extract keys for something that doesn't even exist?

[jessaustin]

The authoritarians would like to be able to torture and imprison you based on nothing more than their whim, so that's why they set it up this way.

The authoritarians' apologists will probably note that to address your concerns, you should use random data first, to whatever extent you think will thwart recovery efforts, and then zero out your empty space.