Key Management Scheme for Smart Grid

A Smart Grid (SG) is a modern electricity supply system. It uses information and communication technology (ICT) to run, monitor and control data between the generation source and the end user. It comprises a set of technologies that uses sensing, embedded processing and digital communications to intelligently control and monitor an electricity grid with improved reliability, security, and efficiency. SGs are classified as Critical Infrastructures. In the recent past, there have been cyber-attacks on SGs causing substantial damage and loss of services. A recent cyber-attack on Ukraine's SG caused over 2.3 million homes to be without power for around six hours. Apart from the loss of services, some portions of the SG are yet to be operational, due to the damage caused. SGs also face security challenges such as confidentiality, availability, fault tolerance, privacy, and other security issues. Communication and networking technologies integrated into the SG require new and existing security vulnerabilities to be thoroughly investigated. Key management is one of the most important security requirements to achieve data confidentiality and integrity in a SG system. It is not practical to design a single key management scheme/framework for all systems, actors and segments in the smart grid, since the security requirements of various sub-systems in the SG vary. We address two specific sub-systems categorised by the network connectivity layer – the Home Area Network (HAN) and the Neighbourhood Area Network (NAN). Currently, several security schemes and key management solutions for SGs have been proposed. However, these solutions lack better security for preventing common cyber-attacks such as node capture attack, replay attack and Sybil attack. We propose a cryptographic key management scheme that takes into account the differences in the HAN and NAN segments of the SG with respect to topology, authentication and forwarding of data. The scheme complies with the overall performance requirements of the smart grid. The proposed scheme uses group key management and group authentication in order to address end-to-end security for the HAN and NAN scenarios in a smart grid, which fulfils data confidentiality, integrity and scalability requirements. The security scheme is implemented in a multi-hop sensor network using TelosB motes and ZigBee OPNET simulation model. In addition, replay attack, Sybil attack and node capture attack scenarios have been implemented and evaluated in a NAN scenario. Evaluation results show that the scheme is resilient against node capture attacks and replay attacks. Smart Meters in a NAN are able to authenticate themselves in a group rather than authenticating one at a time. This significant improvement over existing schemes is discussed with comparisons with other security schemes