Increasing connectivity of electric power grid substation networks has led to concerns about the security of multicast communications on the substation networks. New research shows how suitable design based on IPsec can provide security with low latency.
Smart grid technologies have introduced a variety of capabilities to electric power substations to link Intelligent Electric Devices (IEDs) through digital substation Local Area Networks (LANs) based on Ethernet. Such substations use multicast to send data and control commands between IEDs. At the same time, these substations have become increasingly connected to external systems and hence to threats of malicious attacks. This make it desirable to provide for secure multicast communications in which messages are authenticated and possibly even encrypted. Ideally one could use off-the-shelf security technologies such as the Internet Security Protocol (IPsec) to address this need, but there are two problems: (1) increasing complexity of substation configurations and the complexity of IPsec configuration make automated support of security configuration critical and (2) the latency requirements of substation communications must be respected by security protocols.
Research by Jianqing Zhang, a PhD student at the University of Illinois, and I has shown how to address these problems through the use of an extension of the Substation Configuration Language (SCL) called SecureSCL and a proper application of IPsec Group Domain of Interpretation (IPsec GDOI). Zhang’s technique adds annotations to SCL configurations and uses them to generate IPsec configurations. We produced a mathematical model of the configuration that supports basic tests of correct configuration. One of the most interesting aspects of the project was the discovery that a naïve application of point-to-point IPsec using a hub-and-spokes model is not efficient enough to maintain substation latencies. We did a experiments with various sizes of emulated substations on the DETER test bed and found that scalability depends on effective use of the underlying parallelism of the switches. Zhang used the TVA Bradley substation as a guiding test case for the studies.
The work is described conference and journal articles as well as his thesis. Doctor Zhang is now a research scientist at Intel Labs in Santa Clara where he works on the security of smart grid technologies for home appliances. Here is a link to his home page.
- Application-Aware Secure Multicast for Power Grid Communications, Jianqing Zhang and Carl A. Gunter. International Journal of Security and Networks (IJSN), volume 6, number 1, 2011.
- Application-Aware Secure Multicast for Power Grid Communications, Jianqing Zhang and Carl A. Gunter. IEEE International Conference on Smart Grid Communications (SmartGridComm ’10), Gaithersburg, MD, October 2010.
- Secure Multicast for Power Grid Communications, Jianqing Zhang, Doctoral Thesis, University of Illinois, September 2010.
The following illustrations depict the typical architecture of an advanced electric substation LAN and the SecureSCL system respectively.