Securing Data Communication Through MQTT Protocol with AES-256 Encryption Algorithm CBC Mode on ESP32-Based Smart Homes

The Internet of Things (IoT) is a technology that allows connection between devices using the internet to collect and exchange data with each other. Privacy and security have become the most pressing issues in the IoT network, especially in the smart home. Nevertheless, there are still many smart home devices that have not implemented security and privacy policies. This study proposes a remote sensor control system built on ESP32 to implement a smart home through the Message Queuing Telemetry Transport(MQTT) protocol by applying the Advanced Encryption Standard (AES) algorithm with a 256-bit key. It addresses security issues in the smart home by encrypting messages sent from users to sensors. Besides ESP32, the system implementation also uses Raspberry Pi and smartphone with Android applications. The network was analyzed using Wireshark, and it showed that the message sent was encrypted. This implementation could prevent brute force attacks, with the result that it could guarantee the confidentiality of a message. Meanwhile, from several experiments conducted in this study, the difference in the average time of sending encrypted and unencrypted messages was not too significant, i.e., 20 ms.