Hidden communication systems and weird networks protect against spying – messages can even be hidden in 5G signals and background noise

Hiding information and presence has always been a cornerstone for human survival. As writing became more common, the first encryption keys were developed. The most famous is the code that Julius Caesar used in his correspondence. The predecessor of digital encryption algorithms was the Enigma device of Nazi Germany.

“Inevitably, the need to protect communications is transferred to the information society. Hiding information and communications is increasingly important to protect society. Now, the next step is how to utilise artificial intelligence in a way that combines hiding and encrypting,” says Jyrki Huusko.

On the Internet, a long-used method for securing communications alongside encryption is the Tor network, which hides communications endpoints. However, a third party can detect the existence of data traffic itself. A powerful attacker or government agency can monitor traffic at the exit and entry points and compromise anonymity, but the end-to-end encryption that is normally used keeps the content of communications secure at least for the time being.

When it is necessary to ensure that communications go unnoticed, it calls for new kinds of solutions provided by Hidden Communications Systems (HCS) and weird networks. Both are valuable when there is a need to protect against espionage, for instance, for individuals and organisations in authoritarian countries. Research of covert communications also serves the needs to detect and deter hostile states or criminals who use it.

Hidden communications networks or channels are designed to function completely undetected, for example, in 5G networks. They can provide strong protection for user identity and data privacy. The purpose is not only to hide the content of communications, for instance, with encryption, but also the very existence of communications.

“A similar strive to hide the existence of telecommunications is evident in data breaches. Data is often not exported directly, but it is slipped out gradually among the protocols of other data traffic,” Huusko compares.

Weird networks refer to surprising communication pathways that deviate significantly from standard network architecture. Various telecommunications side channels, light, sound, images, videos or even biological methods may be used for data transfer. The most common is to use non-standard communications protocols.

An important feature of weird networks is that they are usually application agnostic. In other words, the same communication channel can support different use cases, such as communications that must be protected from censorship or used for the critical infrastructure.

Two complementary approaches can be used to hide communications: steganography and obfuscation. Both have centuries of a history. Steganography means hiding the existence of communication as part of other data or signals that appear to be normal. In obfuscation, communication is visible, but its meaning, structure or purpose is made very difficult to interpret.

For instance, Huusko has examined the possibilities of utilising standard control signals in 5G networks to hide communications. By using obfuscation, messages could be hidden, for example, in so-called handshake signals of the opening phase of connections.

“In this case, the handshake basically goes a little wrong or is mistimed, i.e. it is delayed, but only the external recipient can know what has happened and can interpret the hidden message. For an outsider, it is very difficult to determine whether it is a random anomaly, such as a network error or delay, or something intentional,” Huusko says.

He has compared alternatives included in 5G technology to explore how quickly they could be developed into a useful method and what advantages or problems they entail. The choice of the appropriate method depends on whether it provides sufficient protection or whether it is immediately recognised that something odd is going on. Some methods have such a low capacity for hidden communication that they would not be useful for the transmission of a larger data volume. Some technologies to hide data traffic might mess up the entire 5G or 6G system.

Originally, steganography used to blur messages referred to messages hidden in images, but today its meaning extends to radio waves, music and videos. Huusko is pondering even “internet of sound” as one potential area of weird networks.

“Data could be concealed within the background noise of a call or embedded in music by modulated signals in a similar manner that is used for audio file watermarking. Already with current technology and AI tools, it would be possible to generate hidden messages in images and videos almost in real time,” he says.

Generally, AI algorithms and agents can help generate hidden communications. Similarly, AI-based analysis may be the only way to detect cleverly concealed communications.

“Combining hidden communications systems, generative AI and software-defined radio could enable novel radio waveforms and protocols. Just as generative waveforms, hidden communications could better adapt to the environment. For instance, if it is raining, artificial intelligence could determine what type of waveform or signal encoding should be used, but also what would be the appropriate hidden communication method,” Huusko tells.

He estimates that the 6G network system under development could, in principle, include native support for hidden communication AI agents or other features to manage hidden traffic or protocols. The first applications are in the defence sector, where methods to conceal communications and evade radio interference are sought in any case. A significant challenge is to synchronise the radio transmitter and receiver to ensure the message is successfully passed.

“In the future world, there may be a situation where AIs are fighting each other in communications networks. The battle between AI agents rises to the forefront. This raises the question what is the role and capability of humans to control the situation,” says Huusko.

Currently, new solutions for unconventional network architectures and hidden communications are mainly in the conceptual research phase, but their technological maturity is growing rapidly. Additionally, the importance of the solutions is growing as the needs for technological and societal resilience increase, among other things. VTT actively monitors the development of the field, utilises its existing technological capabilities in examining the topic and develops its own solutions as part of broader telecommunications and cybersecurity research.

Are you interested to take a closer look at VTT’s world-class communications services? More information about next generation network solutions can be found here:

https://www.vttresearch.com/en/ourservices/beyond-5g-and-6g-networks