What kind of digital / cryptographic signing would make it possible to create a camera that cryptographically signs the photos it takes so that the images can be verified to have been taken with that specific camera?
The motivation is that if the camera is able to implement a trust system, then it would create the ability to trust that photos or videos that it creates have not been subsequently modified.
Some potential variables:
Would it be preferred to use a single signing key for all cameras of a specific model, vs. keys for each instance of the camera, and how to limit the ability to extract/steal those keys. I guess this might involve a Trusted Platform Module, but I'm not knowledgeable about hardware security.
Out of scope for this question: The trust would be limited by the ability to present false image data to the camera at a stage prior to the signing step, using hardware hacking or simply holding up another image in front of the sensor.
Instead of implementing this as hardware, implement it as a smartphone app and take advantage of existing platform security.