In Chapter 2, Building and Configuring Your Own MQTT Server, you have learned about the MQTT protocol, how a topic is constructed, and how to install and configure a mosquitto broker. At that time, you used a local configuration file to add a user and a password to be used as an authentication method for a local broker. How about the time the packets are travelling from your ESP8266 module to a cloud mosquitto instance? To encrypt the packets, you need to enable security on mosquitto and send encrypted packets from your ESP8266.