This is an example of using HTTPS with CA cert authentication. It is also available in the IDE File | Examples menus.
https://github.com/esp8266/Arduino/tree/master/libraries/ESP8266WiFi/examples/HTTPSRequestCACert
This is an example of using HTTPS with CA cert authentication. It is also available in the IDE File | Examples menus.
https://github.com/esp8266/Arduino/tree/master/libraries/ESP8266WiFi/examples/HTTPSRequestCACert