YOUR_DYNAMIC_KEY is the Dynamic key from Settings → API → Dynamic API. On the dashboard, that value is already in the example, so you only replace it here if you copied this page instead. locker is the URL of the base link you created. destination is the page this visit should open. response is the link you share. It is the base URL with ?r= added.
r is hex. It’s a 12-byte IV, which is 24 hex characters, followed by the AES-256-GCM ciphertext and its 16-byte auth tag. The JSON inside it is {"targetUrl": "https://example.com/page"}.
If r is missing, invalid, or it was encrypted with a different key, the visitor is sent to the link’s saved destination. A bad r doesn’t break the link.
If you leak or expose your Dynamic key, contact support and ask for a reset. You can’t rotate it yourself, and a reset turns the old key off immediately.
