Technology

It needs to be more general. A video should have multiple signatures. Each signature relies on the signer's reputation, which works both ways. It won't help those who don't care about their reputation, but will for those that do.

A photographer who passes off a fake photo as real will have their reputation hit, if they are caught out. The paper that published it will also take a hit. It's therefore in the paper's interest to figure out how trustworthy the supplier is.

I believe canon recently announced a camera that cryptographically signs photographs, at the point of creation. At that point, the photographer can prove the camera, the editor can prove the photographer, the paper can prove the editor, and the reader can prove the newspaper. If done right, the final viewer can also prove the whole chain, semi-independently. It won't be perfect (far from it) but might be the best will get. Each party wants to protect their reputation, and so has a vested interest in catching fraud.

For this to work, we need a reliable way to sign images multiple times, as well as (optionally) encode an edit history into it. We also need a quick way to match cryptographic keys to a public key.

An option to upload a time stamped key to a trusted 3rd party would also be of significant benefit. Ironically, Blockchain might actually be a good use for this. In case a trusted 3rd can't be established.