Evaluating Secure Variants of the MQTT Protocol on Resource-Constraint Devices for Precision Agriculture

When it comes to securing IoT communication, it is critical to employ secure communication technologies that can ensure that sensitive information exchanged between IoT devices and fog/edge/cloud services remains confidential. Since typical IoT devices are resource-constraint, it is challenging to use and deploy secure IoT protocols on such devices: It is thus critical to study the overhead of such protocols for resource-constrained devices, as it significantly affects the performance of an overall IoT solution. In this paper, we analyze the secure variants of the widely used messaging protocol MQ Telemetry Transport (MQTT), namely MQTT with TLS and MQTT with AES. We report the results of our performance evaluation in the context of an IoT solution for Precision Agriculture using an STM32 microcontroller with an NB-IoT module to compare these variants with plain MQTT and determine the most appropriate options based on the amount of data transmitted and achieved security level.