I can imagine Apple doing some kind of hardware-level signing of camera and video data, so that any image shot by an iPhone/iPad would have a signature declarin

I can imagine Apple doing some kind of hardware-level signing of camera and video data, so that any image shot by an iPhone/iPad would have a signature declaring that is was not edited by the user in any way. This exists, and is why the (Canon?) cameras used by police departments at crime scenes are so expensive.