DLKS-MQTT: A Lightweight Key Sharing Protocol for Secure IoT Communications

The increasing reliance on Message Queuing Telemetry Transport (MQTT) as a lightweight messaging protocol for Internet of Things (IoT) applications requires robust security mechanisms that address resource constraints while ensuring data integrity, confidentiality, and authenticity. This paper proposes the Dynamic Lightweight Key Sharing for MQTT (DLKS-MQTT) mechanism, a novel approach that integrates ephemeral key generation, streamlined authentication, and lightweight cryptographic operations to enhance the security of MQTT-based IoT communications. The mechanism employs a 128-bit key generated using a Linear Congruential Generator (LCG), providing robust resistance to brute-force and cryptanalytic attacks while maintaining computational and energy efficiency. Through extensive performance evaluations, DLKS-MQTT demonstrates significant improvements: reducing CPU energy consumption to 0.000002 mJ, achieving an execution time of 0.40 s, and minimizing communication overhead to 60 bytes, outperforming existing methods such as Dynamic Lightweight Authentication for MQTT (DLA-MQTT), Improved Ciphertext Policy-Attribute-Based Encryption (ICP-ABE), and Secure MQTT (SMQTT). The use of ephemeral session keys and nonces ensures protection against replay and Man-in-the-Middle (MitM) attacks, whereas lightweight hashing guarantees message integrity without burdening resource-constrained devices. This work establishes DLKS-MQTT as a practical, scalable, and secure solution for modern IoT networks, offering a balance between performance and security.