SSL certificate verification on ESP8266 Wemos D1 Mini with MQTT broker

Question

I have a raspberry pi 3 with raspbian stretch as its operating system. I have installed and fully configured a MQTT broker on the raspberry pi following this tutorial: https

Answer 1

One of 2 options

1. The WiFiClientSecure includes a list of public CA certs and is verifying your certificate against this list
2. The WiFiClientSecure defaults to not verifying remote certs by default.

Looking at this issue it looks like option 2 is most likely as it implies you have to verify the cert yourself after the connection.