Proof of Disclosure? Is there such a thing? Let's say I have a document. I want to give you a copy, and then I want to prove that I gave you a copy. Ie, I want some kind of digitally signed receipt from you. If you're dishonest, you may receive the document and then refuse to give me a receipt. I would like some sort of cryptographic protocol that provides some sort of "simultaneous swap" - I give you a document, you give me the receipt. Does anything like this exist?

PS. I'm happy to do the research myself, but I have no idea what terms to google for. "Proof of disclosure" definitely isn't the right search term.
You could probably achieve this with a distributed ledger (e.g. a blockchain). If you were to have an image taken of your document recipient holding the document, otherwise you would take the document back immediately or nullifying its effect (e.g. revoke a digital signature on the document that would've been useful for the recipient), and hash that image, and place that onto said ledger, you would have proof that you disclosed information to the recipient. The importance is that due to distribution, the record is redundant, immutable, and most importantly, irrefutable. This method could also be used as a proof of chronology.

One example of this is Bitcoinproof, a method of hashing image data into a Bitcoin address, and sending either a small transaction or no bitcoins to that address. By doing so, the transaction can be mined into a block, becoming a permanent record that can be verified using an image.

Finding the image hash as a Bitcoin address (SHA-256, RIPEMD-160, and base58check), which will have likely only 1 transaction to it, with a timestamp that cannot change, i.e. a proof of chronology. This can also be used as a proof of disclosure, as you mentioned.

That is, unless you're exceptionally good at Photoshopping an image of your recipient into holding your document.

And it might fail, if you lose the photo, or if the network becomes less popular.

Also, this wouldn't be good for private information. You would be using a public ledger, so in the event the receiver disputes your claim, you would have to reveal the information to the public in order to prove this. This means that the document is only good for gaining one time access to a system, through a digital signature.