+ * 5.16 What about Plausible Deniability?
+
+ First let me attempt a definition for the case of encrypted
+ filesystems: Plausible deniability is when you hide encrypted data
+ inside an encrypted container and it is not possible to prove it is
+ there. The idea is compelling and on first glance it seems
+ possible to do it. And from a cryptographic point of view, it
+ actually is possible.
+
+ So, does it work in practice? No, unfortunately. The reasoning used
+ by its proponents is fundamentally flawed in several ways and the
+ cryptographic properties fail fatally when colliding with the real
+ world.
+
+ First, why should "I do not have a hidden partition" be any more
+ plausible than "I forgot my crypto key" or "I wiped that partition
+ with random data, nothing in there"? I do not see any reason.
+
+ Second, there are two types of situations: Either they cannot force
+ you to give them the key (then you simply do not) or the can. In
+ the second case, they can always do bad things to you, because they
+ cannot prove that you have the key in the first place! This means
+ they do not have to prove you have the key, or that this random
+ looking data on your disk is actually encrypted data. So the
+ situation will allow them to waterboard/lock-up/deport you
+ anyways, regardless of how "plausible" your deniability is. Do not
+ have a hidden partition you could show to them, but there are
+ indications you may? Too bad for you. Unfortunately "plausible
+ deniability" also means you cannot prove there is no hidden data.
+
+ Third, hidden partitions are not that hidden. There are basically
+ just two possibilities: a) Make a large crypto container, but put a
+ smaller filesystem in there and put the hidden partition into the
+ free space. Unfortunately this is glaringly obvious and can be
+ detected in an automated fashion. This means that the initial
+ suspicion to put you under duress in order to make you reveal you
+ hidden data is given. b) Make a filesystem that spans the whole
+ encrypted partition, and put the hidden partition into space not
+ currently used by that filesystem. Unfortunately that is also
+ glaringly obvious, as you then cannot write to the filesystem
+ without a high risk of destroying data in the hidden container.
+ Have not written anything to the encrypted filesystem in a while?
+ Too bad, they have the suspicion they need to do unpleasant things
+ to you.
+
+ To be fair, if you prepare option b) carefully and directly before
+ going into danger, it may work. But then, the mere presence of
+ encrypted data may already be enough to get you into trouble in
+ those places were they can demand encryption keys.
+
+ Here is an additional reference for some problems with plausible
+ deniability: http://www.schneier.com/paper-truecrypt-dfs.pdf I
+ strongly suggest you read it.
+
+ So, no, I will not provide any instructions on how to do it with
+ plain dm-crypt or LUKS. If you insist on shooting yourself in the
+ foot, you can figure out how to do it yourself.
+
+