Better just to stick with the social, and tell people that violating the rules will result in disqualification and a ban.
I mean, a camera manufacturer could issue a digitally signed certificate that this key should be only embedded in a particular camera, but it doesn't prove that a copy wasn't made beforehand or extracted from that camera, or that someone wasn't able to misuse the manufacturer's signing keys to sign a few extra keys to be sold to e.g. propaganda manufacturers.
But given that any idiot can fake a picture of Obama \ Trump / shaking hands with <insert here> it would be nice to have something that easily and automatically gets repudiated 99% of the time - we want to default trust not default distrust. Life is much much harder the other way round and design society to promote what makes society stronger is a good thing.
But ultimately photography becomes a sport - yes it's possible to run faster / lift more if you take the drugs. But we ban that because of reasons, much like I suspect competitions will ban AI content and possibly so will newspapers.
(which is why the above signing of images might be a huge step forward)