Up until now, I believed that TLS authentication and encryption can only be achieved when both the client and server exchange certificates with each other initially? Now I am seeing an example in Python code where an MQTT client is communicating with an MQTT broker, but only the MQTT broker provides a certificate.
How then does the encryption take place, if only the broker has a certificate? How are the session keys for encryption communicated in the first place securely? Thanks in advance.
