1. Not everyone should reach every door

Authentication asks “who are you?” Integrator identification asks a prior question: “should a client like you even be talking to this surface?” Restricting integration endpoints to an allow-list of known origins shrinks the attack surface before authentication is even attempted — an unrecognized client is turned away at the door, not invited to start guessing credentials.

2. A complement, not a replacement

Origin allow-listing does not replace authentication; it precedes and reinforces it. It limits who can probe the integration surface, reduces credential-stuffing and reconnaissance noise, and means a leaked credential is useless from an origin that is not on the list — defense in depth for machine-to-machine traffic.

3. How B5 Secure handles it

B5 Secure rejects connections from clients outside the configured origin allow-list, working with IP binding and scoped keys so an integration surface is reachable only by the clients it was built for.