Truecrypt had this exact function - one password would decrypt your drive sort of on one end, and start the OS there, another password would decrypt the drive on the other end, and start the OS installed there - so you always had perfectly plausible deniability, since the drive taken as a whole looked like a completely normal encrypted drive(in fact you could accidentally destroy the hidden partition by overwriting "empty" area while booted into the non-secret OS). Always thought that was super cool.

> perfectly plausible deniability

The paranoid dystopian counterpart is that you cannot prove you don't have a second partition either. Might get awkward if someone decided to compel the second password on less solid evidence. If you're not actually using the feature.

There was a case here in Germany where the police report revealed that they apparently spent a lot of time looking for evidence of a hidden partition/encrypted data etc because a PC owned by single man with zero evidence of porn was unusual. (but didn't find anything in the end, and didn't claim anything they didn't have evidence for)

this is why you should actually have "signs of life" and something _slightly_ illegal on your plausible deniability partition. Just enough dirt to get you into trouble, but not too much trouble. If you're squeeky clean, you get the rubber hose cryptography treatment.

Ah, the magical porn partition.

Level of kink up to you.

If you want those signs of life to be convincing, it should include all kinds of history without long gaps, such as:

- email, including recently received and sent emails

- web browser history

- system logs

- software updates

In practice, I think it’s impossible to do that. If the police discovers, for example, that your system logs show your machine was off for a week, but they also just saw you reset it, what do you tell them?

>>but they also just saw you reset it, what do you tell them?

That you're not a computer expert and have no idea why your computer wasn't keeping logs correctly?

not an expert, yet you set up an encrypted partition?

Yeah, there was a tutorial online. Thought it was a good idea in case my laptop got stolen. Don't need to be an expert to click through an automated wizard, do I?

"rubberhose him just to be sure"

this is a real problem, yes; i find encrypted volume in swap partition actually provides better plausible deniability. "I was told it should be 2x the size of RAM," - says a guy with 512G of ram and swapoff.

The only problem is this is sort of obvious from a forensics perspective. Person is using truecrypt, they boot it up for you, and the partition is only half the size it should be.

No, like the other reply pointed out too - it's not obvious. The first password unlocks the entire partition, the hidden one is just within the "empty" area of the drive. If you write a sufficiently large file while running the OS you could just overwrite and destroy the hidden partition without knowing that you did so. It's also impossible to tell that the hidden parition is there because encrypted data is indistinguishable from encrypted empty area of the drive.

Since Truecrypt bailed without explanation, do you know if Veracrypt also has this feature?

It does. Veracrypt is basically Truecrypt with some new features as far as I've been able to tell.

After TC killed the project (for all intents and purposes) is there the ssme level of trust in VC?

The question always was what kind of attack are you trying to guard yourself against. I imagine top level agencies have a way to crack truecrypt/veracrypt encrypted volumes, but I also imagine they aren't using that capability against just anyone to not show their hand and risk the issue being fixed.

Your parent seems to point out that's not how it works: you've got access to the ful partition either way, meaning you can accidentally overwrite the other partition.

If I remember right, the hidden partitions are indistinguishable from random data on your disk and it was necessary to provide an offset to the first block (or whatever) so it could be decrypted. You could easily overwrite it accidentally because it just looks like free space.

Disclaimer: I know next to nothing about OS'es and login and so on.

I had an idea once, would it be possible to set up two sets of passwords? One to properly unlock your device, and one to trigger either encryption or scrambling of the data when entered?

Of course, this is a kill switch, but that's usually detectable if the attacker is sophisticated enough. Plus, they can always backup the disk before.

Plausible deniability lets you pretend you do not have incriminating data, but it's tricky to use in the first place: https://gitlab.com/cryptsetup/cryptsetup/-/wikis/FrequentlyA...

Travelling with an empty disk seems like a more appropriate option. Dm-verity could probably be used to check that there has been no tampering.

In software, where there's a will, there's a way.

Darknet Diaries has a cool episode about the dark cellphone industry: https://darknetdiaries.com/episode/105/

Of course, but this won’t be easy with commodity hardware. Standard practice is to use write-blockers to prevent this kind of tricks, but of course you can prevent write-blockers by integrating your storage.

I think you could get a pixel phone to do this in a useful way.

Lookup "duress passwords"

* https://en.wikipedia.org/wiki/Duress_code

The feature is more relevant in (full disk) encryption software than OSes.

Have I got a PAM module for you: https://github.com/nuvious/pam-duress

The problem is, if they are serious and suspect you might be prepared and technical savvy, they will never allow you to operate the device.

Yep. Pretty much all nerd solutions to physical or legal threats are genius but also worse than useless. Here's a $5 hammer, hit him with it until he gives us what we're looking for, so goes the comic I saw once.

This is effective against legal threats. I remember at least one case in my country where one person was saved by truecrypt. They even asked the FBI for help on decrypting it.

Hopefully civilization is not so far gone that police will imprison, torture or kill for failing to incriminate themselves. If it gets to the point cold-blooded torture is on the table, you'll probably get killed anyway.

That’s why it needs to be destructive. You can’t beat access to something out of someone if it has been deleted.

While true, they may beat you anyway just to be sure.

Big opportunity to implement a kill-switch if the microphone recognizes your screams!

> Here's a $5 hammer, hit him with it until he gives us what we're looking for, so goes the comic I saw once.

You are probably thinking of the $5 wrench in https://xkcd.com/538/

That's referred to as rubber hose cryptography.

That's also why Assange (and others) developed the Rubberhose file system[0].

It's based on the game theoretic idea that if your adversary has no way of knowing how many hidden partitions you have, then you have no way of proving to them that you've given them all your secrets.

As such, there is no benefit to you revealing any secrets under torture, because the torture would continue even after you've told them everything, therefore there is no point to them torturing you in the first place.

[0] https://en.wikipedia.org/wiki/Rubberhose_%28file_system%29

"JOB OPPORTUNITY: Assassins and mercenaries required. Must be proficient in game theory".

In reality they will torture you until you stop decrypting partitions, and then a bit more of special torture, just in case.

If they don't understand game theory, that just means they will act sub-optimally. In any case, the correct strategy for the user is still to not decrypt any partitions, since, as you say, the sooner the user stops decrypting, the sooner the torturers give up.

I don't think either of has met someone who engages in actual torture, but I imagine they rarely, if ever, “give up”.

That seems like a pretty foolish assumption to make of your adversaries/captors.

If a torturer has good reason to believe you have valuable information regarding subject X, they'll simply torture you until they possess that information or you die. If you don't possess the information, you're screwed. If you do possess the information, it's likely that they'll stop after they get what they're after.

A state liable to torture you may simply kill you instead. Or torture you and kill you, even if it serves no particular purpose.

If you're in the business of protecting your secrets against torture then you need to also be protecting them against death because that is grimly inevitable.

"I don't think they wanted me to say anything. It was just their way of having a bit of fun, the swines."

That's not really making the case for clever crypto solutions. Assange is rotting in prison and is probably going to die in the US in the near future. What secret information could he be protecting at this point?