[pavel_lishin]

Haven't people suggested this with regards to TrueCrypt's hidden volumes, with "rubber-hose cryptography" being the most common answer, and "yeah, well, prove that this is your REAL phone unlock code" being the second most common.

[baddox]

Rubber hose cryptography isn't a valid response to plausible deniability, because it applies equally to a volume that's encrypted normally (i.e. the cops just see junk data). At least you have a chance to throw them off with your fake unlock. Anyway, if it comes down to torture, you're screwed no matter what (unless you're trained to withstand torture); plausible deniability is more for "civilized" courts because they can't possibly prove that you're withholding anything. Personally, I think the 5th amendment in the USA should mean you can't be compelled to decrypt your data anyway, but that's not how the courts see it.

[JohnQPasserby]

actually that is how the courts see it

[Karellen]

I think you mean rubber-hose cryptanalysis.

I am amused by the idea of rubber-hose cryptography though - beating on the data until it encrypts itself!

[pavel_lishin]

Actually, an actual example would be cutting out someone's tongue to prevent them from speaking.

(Obviously this only worked for illiterates.)

[Karellen]

That wouldn't be cryptography (hidden writing). It would be cryptology (hidden speech, from "logos" rather than "graphos") or alogy (lack of speech).

/pedant

(sorry)

[tadfisher]

Prove that it isn't, officer.

[pjscott]

With that, you've just admitted that you're aware of the possibility of setting up multiple profiles with different unlock codes. Be careful what information you leak when you're trying to look innocent!

[burgerbrain]

How so? The officer was the one that suggested the possibility in this scenario.

[kaybe]

Yes, but the answer shows that you were aware of it before, which means you have already come in contact with the concept, leading to a higher probability for you to actually use it.

[tjoff]

Then again, a tech savvy user that encrypts his drive and claims he/she haven't a slightest idea what the officer is talking about is probably in many cases way more suspicious. At least to an officer that is informed enough to bring that up.

[kaybe]

Depends. How closely linked are the concepts of simple encryption and plausible deniability encryption? If you start researching the topic a bit you will stumble upon both, but if, say, a friend installed it?

[burgerbrain]

I don't think that it does. I think the most it can be said to demonstrate is that you are aware of how the burden of proof is supposed to work in the United States.

In other words, it's his job to prove things, not yours.

[kaybe]

Yes, but it implies much more than just that; defiance for example. You don't want to egg them on, do you?

[lsb]

No cellphones are allowed in top secret military locations in the US, because all can be remotely signalled to start recording audio. We know they'll turn a phone into a bug if they need to, so it's foolish to assume they wouldn't be able to get the real PIN.

[schiffern]

Do you have any evidence that indicates that this is the reason?

A much more likely explanation for the policy involves abuse by the user, either intentionally or unintentionally. Cameras and USB sticks are similarly restricted.

[pavel_lishin]

Yeah, I'm sure that the Princeton, TX police department has access to CIA-level technology, and will use it to prove that I was texting while driving.