A Bandwidth-Efficient Secure Authentication Module for Smart Grid DNP3 Protocol

DNP3 is one of the oldest and widely used communication protocols for smart power grid, which has been upgraded to DNP3 Secure Authentication (SA) to address the increasing security needs of power grid applications. However, in practice, such upgrade was only deployed for critical operations due to its major overhead while non-critical operations are still not protected. Nevertheless, with the ongoing transformations in power grid, the underlying infrastructure is no longer isolated and needs to support a wide variety of applications. Consequently, this transformation requires applying DNP3-SA for all operations, whether they are critical or not. This requirement creates additional challenges since it will reduce network bandwidth availability by causing additional overhead on communication links especially if the underlying infrastructure is legacy. Therefore, in this paper, we propose a revision for DNP3-SA module to eliminate such overhead concerns on the bandwidth due to security operations. Specifically, we introduce a new authentication module that utilizes dynamic key-generation schemes to support mutual authentication for DNP3 in 0-Round Trip Time (RTT) and provides replay-attack prevention. The evaluation on a realistic low-bandwidth wireless LoRa testbed shows that the proposed extensions improve the security of DNP3-SA while significantly decreasing the message overhead of currently used authentication module. Thus, it is suitable for ongoing power grid transformation and supports evolving security needs.

I. Introduction

The existing power grid is becoming smarter (i.e., smart grid) through a major transformation to enhance its reliability, resiliency and efficiency by enabling two-way communication using intelligent electronic devices (IED), sensors, remote terminal units (RTU), distributed energy resources (DER), and dispersed loads [1]. Supervisory Control and Data Acquisition (SCADA) systems are at the heart of it and used to control, manage and monitor various processes to provide high availability, controllability, and maintainability requirements of today’s smart grid infrastructure. To govern various power-grid components, several standards were developed over the years to provide communication within SCADA [2], such as Distributed Network Protocol (DNP3), Modbus, Object Linking and Embedding for Process Control (OPC) and Intercontrol Center Communications Protocol (ICCP) [3]. As an IEEE-1815 standard, DNP3 [4] is actually still one of primary protocols deployed in the current smart-grid systems to convey information within the US power grid infrastructure.