Comparing MQTT and gRPC Protocols Performance in a IoT Smart Campus Cybersecurity Scenario

This paper presents a performance evaluation between MQTT and gRPC in a secure Internet-of-Things (IoT) architecture for Smart Campus deployments. Identical sensing systems were instrumented with TLS 1.3, AES-128, and HMAC. After an exploratory run, a one-week campaign enabled a statistical comparison of latency, payload size, and total message size bytes. Results show no statistically significant difference in mean latency, indicating comparable delay under security. In contrast, gRPC produced smaller messages compared to MQTT. These savings stem from compact Protocol Buffers encoding and persist with encryption and authentication. Overall, when a gateway architecture is acceptable, gRPC offers large bandwidth/overhead reductions without a latency penalty, making it a strong option for secure campus-scale IoT. Future work includes scalability and energy-cost evaluation, fault tolerance, and the use of Decentralized Identifiers (DIDs) for device authentication.