# A Secure and Scalable Authentication and Communication Protocol for Smart Grids
###### Abstract  
The growing adoption of smart grid systems presents significant advancements in the efficiency of energy distribution, along with enhanced monitoring and control capabilities. However, the interconnected and distributed nature of these systems also introduces critical security vulnerabilities that must be addressed. This study proposes a secure communication protocol specifically designed for smart grid environments, focusing on authentication, secret key establishment, symmetric encryption, and hash-based message authentication to provide confidentiality and integrity for communication in smart grid environments. The proposed protocol employs the Elliptic Curve Digital Signature Algorithm (ECDSA) for authentication, Elliptic Curve Diffie-Hellman (ECDH) for secure key exchange, and Advanced Encryption Standard 256 (AES-256) encryption to protect data transmissions. The protocol follows a structured sequence: (1) _authentication_--verifying smart grid devices using digital signatures; (2) _key establishment_--generating and securely exchanging cryptographic keys; and (3) _secure communication_--encrypting and transmitting/receiving data. An experimental framework has been established to evaluate the protocol's performance under realistic operational conditions, assessing metrics such as time, throughput, power, and failure recovery. The experimental results show that the protocol completes one server-client request in 3.469 ms for a desktop client and 41.14 ms for a microcontroller client and achieves a throughput of 288.27 requests/s and 24.30 requests/s, respectively. Furthermore, the average power consumed by the protocol is 37.77 watts. The results also show that the proposed protocol is able to recover from transient network disruptions and sustain secure communication. p 2025 5 11  
and phasor data concentrators (PDCs) to aggregate data from PMUs and to facilitate data sharing with SCADA. Smart grids additionally incorporate distributed energy resources (DERs) [2] such as solar panels, wind turbines, and electric vehicle (EV) chargers, which support the expanding EV market. Advanced supervisory systems, including Advanced Metering Infrastructure (AMI) [3], Supervisory Control and Data Acquisition (SCADA) [4], and Advanced Distribution Management Systems (ADMS) [5], are also integral to enhancing dynamic grid management. This interconnected ecosystem promotes enhanced operational efficiency and optimizes electricity distribution, contributing to a more sustainable approach to energy consumption. These advancements in smart grids require robust communication protocols to protect the integrity and reliability of grid operations. The integration of Internet of Things (IoT) devices into smart grids presents transformative opportunities to enhance grid intelligence, reliability, and overall efficiency [6]. Simultaneously, this integration introduces significant cybersecurity challenges [7; 8; 9]. The communication among devices and supervisory-level data flows within systems such as AMI, SCADA, and Industrial Control Systems (ICSs) are increasingly susceptible to interception and manipulation by malicious actors. Existing standards for smart grid communication, including IEEE C37.118.2 [10] and IEC 61850-90-5 [11], do not specify node authentication, secret key establishment, and secure communication mechanisms, consequently leaving the power grid vulnerable to various cybersecurity threats, including unauthorized access and data tampering. These vulnerabilities not only jeopardize operational safety but also raise significant concerns regarding the overall security of electrical infrastructure.