The Implementation of Encryption Algorithms in MQTT Protocol for IoT Constrained devices

The Internet of Things (IoT) is a promising and emerging technology in which many devices communicate, process, and exchange information with other devices, servers, or applications. The communication link could be between people to devices, or machine to machine, resulting in an extensive network of connected devices. Due to the increase in the range of applications, the attack surface has also increased. Usually, data transfer through an IoT network is critical, so confidentiality is a significant concern. In an IoT network, confidentiality can be achieved using Secure Shell (SSH) and Transport Layer Security (TLS) protocols. However, they have overheads that resource-constrained sensor devices cannot handle. Therefore, lightweight security mechanisms must be incorporated into various protocol stack layers. In this work, we have implemented AES128, Elliptic Curve Cryptography (ECC), ChaCha20, and Corrected Block Tiny Encryption Algorithm (XXTEA) in the MQTT protocol on ESP8266 and ATmega328p IoT devices. We present the performance evaluation of these encryption algorithms on a hardware testbed and a Contiki OS-based cooja simulator using the Tmote Sky module. The hardware experiments show that the ESP8266 chip with XXTEA encryption algorithm embedded with MQTT protocol is more efficient. At the same time, the simulation results show a rise in power consumption if we choose a robust encryption algorithm and increase the number of nodes.