There’s nothing cryptographic about this. It’s a central authority that either says “yes it’s real” or not. The system revolves around trust in that central authority. Everyone can easily fake a certificate which cannot be independently falsified without asking that central authority, who will be more likely to check their books than to do anything related to the actual certificate.
This is the second time in a couple weeks where I've seen a headline try to take a "crypto" angle for something ridiculously simple. There was another article touting drug cartels using "dollar bill serial numbers as random keys", https://news.ycombinator.com/item?id=20484197, which was wrong - the keys weren't random, they were just unique and difficult to fake.
I get the sense, with the general failure of blockchain to live up to its hype beyond Bitcoin, that we'll see a lot of "crypto-" this and that nonsense, similar to how everything was "e-" this and that in 2000.
No, but I think you'll agree that saying tears in a piece of paper "cryptography" is a stretch. It's not cryptography in the same way that a stamp or wax seal isn't cryptography, unless your definition of cryptography is "any method to protect the confidentiality and integrity of a document".
That’s right, the CA certificates in your browser can be tampered with because they aren’t the actual CA saying “yes it’s legit” they are a token containing a cryptographic key which claims to prove authenticity mathematically.
While not actually cryptographic in nature, it's a nontrivial authentication protocol that is better than a more traditional certificate, as discussed in the article, and potentially very impressive end enlightening for the not too technically minded people who follow art and art trade.