IoT devices identifying themselves (authentication) is only a tiny sliver of the security picture. You also need to worry about authorization, encryption, and (security) monitoring.
One really annoying security problem with IoT devices right now is SSL/TLS's complete fundamental incompatibility with the concept of "roaming". Want to connect to your device via SSL/TLS? Better get used to ignoring warnings about the certificate name not matching the device's IP/hostname.