TACK benefits from Convergence, but isn't based on it. It also doesn't require it. Convergence could be used as a source of information on existing pins it has

TACK benefits from Convergence, but isn't based on it. It also doesn't require it. Convergence could be used as a source of information on existing pins it has seen, but TACK is still useful even if it's just supplied by the website itself. Think of it like ssh known-hosts, but with the added feature that the server side (sshd) can securely tell you to stop using an old entry in known-hosts and use a new one instead when its server key changes. Also, TACK is not certificate pinning. It's public-key pinning (the thing inside the cert). You can change certs all you want without changing the public key, and the same TACK pin will be valid for all of them. This is better than cert pinning since you can change CAs without having to redo all your cert pins.