Information and Communication Technologies (ICT) support the digital evolution of energy networks, enabling automated and intelligent operations. Internet of Things (IoT) devices enable remote automated measurements and data collection, improving anomaly detection, predictive maintenance, and operational efficiency. When IoT devices communicate with each other, they need to be authenticated within the network. Traditional authentication methods rely on certificates issued by a centralized Certificate Authority (CA), which can pose a single point of failure and be computationally heavy for IoT devices with limited resources.

The paper presents a prototype implementation of blockchain-based public key authentication for IoT devices in the context of electrical monitoring systems. In the proposed solution, IoT devices communicate over a secure channel using a publisher/subscriber protocol (MQTT – Message Queue Telemetry Transport), leveraging Transport Layer Security (TLS) and employing an Algorand Blockchain system. The results of functional tests encourage further investigation into adopting Blockchain systems for IoT device authentication in typical scenarios relevant to the energy transition.