> Being able to prove that you cannot possibly decrypt the partition, moves you out of the XKCD 538 scenario.

It does not. I think your mistake is modelling an adversary willing and enabled to torture like an entity that behaves like you would do, which I assume is according to logic + knowledge + willing/able to communicate + respect for human life.

How about the adversary just not buying your proof and torture you anyway (to death) just in case you are trying to deceive? How about the adversary not even giving you the opportunity to explain or show your proof? (imagine getting yelled "open it" because they don't speak much english other than that and get beaten for whatever you do that doesn't look like "opening it")

I'm writing this just in case someone reading will actually at some point need to prepare for such threat. "Proof of inability to decrypt" (as also "Denial of encryption") does not give you a way out of the "XKCD 538 scenario". If you can't avoid the scenario entirely, there are better bets (e.g., disguise still-encrypted data as plausible, non-sensitive other data).

"in case someone reading will actually at some point need to prepare for such threat"

You mean like any human rights organizations who send people to authoritarian states ?

You mean like any Foreign Ministry sending a courier out in the world ?

You could learn so much about operational security, if you wanted to, just by reading open sources.

Can I recommend you start with a wonderful old article called "A first tour like no other" ?

If your adversary model is a wild-eyed gun-slinging mid-west racists and you are black, then encryption is not going to be a factor in your death, and speculating what you can or cannot convince them about is besides the point.

If a sane adversary has captured you and your devices, say border police in some police-state like Belarus, Brazil or USA, it would be silly to assume that you know more about disk-encryption than they do.

Most importantly, you would be very silly to assume that they will not simply lock you up, until you provide access to the device, aka "XKCD538-lite".

There are people who have languished in hell-hole jails for years already, not because they are unwilling to provide access, but because they cannot provide access, but are unable make a convincing showing of that.

Competent organizations make sure their travelers can make that showing convincingly, and one of the steps they take, is to make 100% sure there is no unexplained high-entropy data on their devices.

Imagine ending up in a foreign jail for years, just because you once deleted a huge gzip'ed file, and the first sectors subsequently got overwritten ?

Yeah, that happened: "Now decrypt this other secret partition!"

You are mixing multiple different scenarios with a combination of statements that apply only to some of them and a bunch of trivial assertions that despite true do not support your point. You failed to understand I never said "proof-of-inability-to-decrypt" is generally useless. On the contrary in facts, it does indeed solve the last scenario you mentioned, which is however not the one you originally described.

To clarify, being held captive "by a sane adversary" until you supposedly decrypt allegedly encrypted data is different from falling into the hands of someone willing and enabled to torture you. Unless you consider torure a "sane" practice. If you cannot understand the difference maybe you should follow your own recommendation and learn a little more.