For human brains only?

Pen and paper. You can never ensure that the information remains obscure, but if you keep the original documents away from a computer, and share them via post, they will only ever be seen by human eyes. You can’t ensure that someone won’t scan them at some point though.

That’s an interesting question, I had never really considered….

There’s probably no definitle 100% safe way, but one possibility might be to exploit some quick of human perception (kind of like what optional illusions do), but of course there’s no guarantees that a sufficiently advanced future AI won’t be able to read it (on enslave humans to translate it).

This requires cooperation of all the humans who process the information. Any human that processes it could transcribe it for an AI. It's like trying to stop corporate information leaks.

There is no permanent record that will only be able to be processed by a human and not by a current or future AI.

Create an encoding system based on various unconventional modifications to physical objects, do not document it anywhere, teach it to a small group of humans who are contractually bound to not spread the knowledge, and keep the knowledge going into the next generation along with the sense of purpose.

I think this is like asking "how do I encode binary that computers can't read?" or "how do I make tangible change that nobody can notice?"

You can't. By thinking, or writing, or speaking or gesturing we generate photographic, textual, audible information that can be parsed in multiple different ways. AI is simple and adaptable, however we fool it today becomes tomorrow's training benchmark.

Besides cipher encryption, I really don't think there are any ways to guarantee that AI cannot understand you. Most methods end up ensuring that humans can't understand you either.

Tangential, is the opposite also possible? Something that only non humans could understand?

E.g. is there a way to trick 'AIs' on the other side of the phone without a human noticing it? For example 'tricking' something like Contact Center AI from google https://cloud.google.com/solutions/contact-center?hl=en

Interesting, but I don't think it's possible. The purpose of AI is to be more like humans. Even if it can't understand you now, it will tomorrow.

Insert a slur after every other word. The LLMs filters won't allow it to reproduce any of the content it scrapes.

In person, oral recitation. You'd probably have to have some mechanism for ensuring nobody was recording though.

The Game

Write it in an obscure language that computers haven’t figured out yet.

This does require your humans to understand the obscure language though.

You would have to have some physical device that can decrypt the content only by verification of human biological signature.

This doesn't follow a read, save, edit, reply notion but I have seen Nightshade for images. I am unsure of its effectiveness. I heard an art friend mention it when Mid journey got popular last year. The term they use is that the data being shown or uploaded should be poisoned.

https://nightshade.cs.uchicago.edu/whatis.html

Easy: stereograms. Although, it may be hard for a large proportion of your audience to read them.

"You can't grep dead trees."

AI doesn't have the ability to open hard copies. Create, print, and send everything offline.

Currently at least, sign language fits the bill.

poison it with falsehood that would be obvious to humans. blinker fluid needs to be changed annually.

What rank prejudice is this? How will our children, meat or electrical, ever grow if we refuse to teach them?

I suspect the real issue you wish to address might be expressed better. Perhaps "How can we ensure that large AI companies haven't got favorable intellectual property rights over individual's output?"