> is a surmountable problem given all the cryptographic technologies at our disposal

I'm genuinely curious, is it? I don't know enough to be sure one way or the other, how you'd do it with some kind of private/public key thing or whatever. Can anyone here provide a quick example?

And I'm assuming it would involve some kind of code generated on the spot just for you, so somebody couldn't just post a code on the internet for all teens to use.