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The White House wants to 'cryptographically verify' videos of Joe Biden so viewers don't mistake them for AI deepfakes
(www.businessinsider.com)
This is a most excellent place for technology news and articles.
You sign them against a known public key, so anybody can verify them.
If it's just the cameras owner attesting, then just have them sign it. No need for expensive complicated circuits and regulations forcing these into existence.
You can't use a MAC for public key signatures. That's ECC, RSA, and similar.