So now that photographs are essentially digital documents and can be digitally signed as such, why aren’t camera manufacturers making cameras which digitally sign the photos they take? The camera would have its own key and the photographer would have her own, too. Both keys would be used to sign the photo, proving that the photo came from that camera and was taken by that photographer. This would bolster the authenticity of a photograph in a world where the art of “photoshopping” can so easily fool people.
Let’s say you take that once-in-a-lifetime photo of Bigfoot, Elvis, Jimmy Hoffa, and Dick Cheney playing pick-up basketball. With the photo signed by the camera as well as you, your photographic proof becomes much more trustworthy. That lets you sell it for big bucks to the National Enquirer rather than settle for the Weekly World News.
Date and time info could be signed as well, though that would only prevent it from being changed as there’s no secure way to verify a clock’s time. No two people on the planet ever agree on what time it is, something no amount of technology will change!
(Bigfoot, by the way, would crush in basketball, even if he was double-teamed. Dunking presents no challenge when you’re 8 feet tall.)