Lightweight Cryptographic and Scalable IoT Systems for Encryption across GSM-MQTT Architectures in Resource-Constrained Aquaculture Environment

Internet of Things (IoT) technologies in environmental monitoring provide real-time remote data acquisition capabilities and decision-making for different domains, including aquaculture. This study investigates a secure water quality monitoring system designed specifically for fish farms through IoT technology with an emphasis on lightweight encryption methods combined with real-time GSM communications. The primary objective is to protect and maintain the confidentiality, integrity, and operational efficiency of vital pH, Dissolved Oxygen (DO), and Temperature (T) measurements collected by low-power microcontroller devices. A wireless data transmission system was based on Arduino with calibrated analog sensors and the SIM800L GSM module to implement the MQTT protocol for data transfer. The data security assessment involved the implementation and testing of the AES-128-CBC and SPECK-128-CBC symmetric encryption algorithms under equivalent real-time circumstances. SPECK-128-CBC delivered faster encryption (209.64 µs) than AES-128-CBC (235.08 µs) along with improved memory efficiency and more compact payloads, indicating its best fit for constrained environments. AES-128-CBC demonstrated a slightly higher level of ciphertext entropy, reaching 5.18 bits/byte compared to 5.09 of SPECK-128-CBC. Using a weighted scoring method that weighted entropy at 40%, processing speed at 30%, and memory and payload efficiency at 30%, SPECK achieved 0.9931 while AES reached 0.9484. These results suggest that SPECK-128-CBC offers an energy-efficient encryption solution to provide optimal security for GSM-based IoT systems in aquaculture environments.