[stanac]

I was thinking the same thing. Apple and Google can start (as tech companies) to add signatures to images. As long as private key doesn't leak we are good. And each manufacturer can have different cert issued by higher authority e.g. Google, so it can be revoked when it leaks. They could include digital camera manufacturers (sony, nicon, canon, ...) and define a standard. Signature can be a meta tag based on hash of the image.

This would limit authenticity to images taken by official software.

[webstrand]

You can still just manipulate the official hardware to produce the image you desire, i.e. record a video that's projected onto a wall. And it'd be fairly easy to do with existing technology too.