NTAG424 DNA explained: why an unclonable tap changes trust

Ordinary QR codes and basic NFC tags share one weakness: they say the same thing every time, so anyone can copy them. NXP’s NTAG424 DNA chip fixes this with SUN — Secure Unique NFC — messages. Each tap generates a fresh cryptographic signature (a CMAC) that a server verifies and will never accept twice.

In practice, that means a counterfeiter can photograph your tag, clone the URL, even lift the QR — and still fail authentication, because they can’t reproduce the next signature. It’s the difference between a label that claims to be genuine and a tag that proves it, on every single tap.