Inspired by one of the mysteries of human perception, a researcher at Oak Ridge National Laboratory (ORNL) in Tennessee has invented a way to hide sensitive electric grid information from cyber attack.

Peter Fuhr, who heads the grid communications and security group at ORNL, was intrigued by synaesthesia. This lifelong condition causes some people to experience one sense through another, such as perceiving sounds as colours. Fuhr applied this concept to encrypting the language of grid management software into colours.

Utilities use a computerised system for gathering and analysing real-time data to monitor and control equipment. That system communicates with hardware using strings of letters. The letters can be translated into colour combinations displayed as bars, wheels or swirls. The colour patterns in turn are faded beneath another image, such as a colourful pointillist painting, or hidden between the frames of a video feed. The decoding key rotates with each sensor reading. It changes based on the Fibonacci Sequence, in which each subsequent number is derived by adding the two previous numbers.

This approach has already drawn attention from private companies interested in licensing the technology, Fuhr said. The concept was tested in the field for six months using a secure link between ORNL and the public utility EPB of Chattanooga. The encoded colours are transferred using communication links among video cameras at EPB’s electrical substations.

“It’s not traveling the IT or operating network, which makes it even harder for bad actors to find,” Fuhr said. “And it’s on the video so briefly, it’s just subliminal.” The conscious mind doesn’t register the image.

A central machine receives these sensor data about temperature, pressure, voltage, current and electromagnetic fields, then decodes them automatically. Anything suspicious will immediately alert the utility’s central equipment control system.

To crack the colour code, Fuhr said, an attacker would have to locate the colour bar, know the equipment’s protocol language and the sensor’s IP address, and rapidly guess the right colour – or letter – combination at the correct point in the Fibonacci sequence.

These layered defences are important for utilities because remote tampering with substation equipment can quickly destabilise the power supply. For example, spoofing a thermal sensor to report a very low temperature might cause fans to shut off. That could cause overheated equipment to fail, triggering a blackout.

More than 100 attacks or incidents of suspicious activity were reported in 2022 at substations across the USA. Although many were physical attacks on equipment, the 70 per cent increase in their frequency has raised public concern and led utilities and elected officials to focus on the threat.

Jim Glass, senior manager for smart grid development at EPB, said it was vital for utilities to have a toolbox of cyber-security approaches.

“What makes cyber security so much more critical is that if somebody can get access to the secure network that operates utility equipment, it would be as if they’d broken into all the substations at once,” he said.

That’s compounded by multiplying points of access to the system: sensors and digital equipment on power poles, smart meters, even smart home technology that utilities may be able to control directly.

Glass said Fuhr’s invention was helpful because it could be combined with various other types of security coding.

“And it doesn’t matter what the communication method is,” Glass said. “You could secure or hide the data this way to make it very difficult for someone to intercept.”

UT-Battelle manages ORNL for the DoE’s Office of Science, the single largest supporter of basic research in the physical sciences in the USA.