Essentially the idea is that you land on the page and an asymmetric keypair is generated for you. You send a link to someone else that contains the public key in the URL. When they go to that link, they can encrypt a payload using your public key (envelope encryption, which I believe is needed for arbitrary payload sizes). They send you the encrypted payload back and you can decrypt in your existing browser session.

So if it's not obvious by now, I'm clearly no cryptography expert, but I know enough to be horrifyingly dangerous :). Can anyone here help me understand where this model breaks down, assuming someone very smart about this stuff were to do the implementation? Thank you!