Maude-HCS helps model and validate covert network designs

Defense contractor RTX, formerly Raytheon Technologies, has open-sourced its Maude-HCS toolkit, a software solution developed for DARPA that enables rapid modeling and validation of hidden communication systems (HCS). The tool, released under the Apache 2.0 license on GitHub, represents a significant advancement in the field of covert network design and testing.

What is Maude-HCS?

Maude-HCS is built using the Maude programming language and represents one of the first generalized, modular tools for experimenting with hidden communication system designs at practical scales. The toolkit was developed as part of DARPA's Provably Weird Network Deployment and Detection (PWND2) program, which focuses on supporting internet freedom and protecting military forces operating in hostile environments.

Hidden communication systems are designed to conceal specific network traffic within the broader flow of internet activity. These systems employ various techniques including protocol tunneling, mimicry, obfuscation, reflection/refraction, cloud fronting, proxying, and steganography. The fundamental challenge in designing such systems lies in balancing performance with the risk of detection by adversaries.

How it works

Traditionally, designing effective hidden communication systems required extensive trial-and-error testing, weeks of research, and significant uncertainty about whether a chosen design would work once deployed. Maude-HCS transforms this process by allowing designers to specify protocol behavior, adversary observables, and environmental assumptions. The tool then generates results across a range of scenarios that can be used to audit claims of undetectability.

The toolkit can predict three critical metrics for any given HCS design: latency, data rate, and operational duration before detection. When compared with physical experiments, Maude-HCS demonstrates an error rate of only 1 to 9 percent. More importantly, analyses that previously took weeks can now be completed in hours.

Practical applications

The implications of this technology extend far beyond military applications. While the primary development context was national security—helping military personnel in hostile areas and supporting internet freedom initiatives—the open-source release makes the tool available to universities, industry partners, and other researchers who want to experiment with secure, anonymous communications tools.

For journalists working in restrictive environments, activists organizing in authoritarian states, or organizations needing to protect sensitive communications, Maude-HCS provides a scientific approach to evaluating different covert communication strategies. Rather than relying on anecdotal evidence or theoretical assumptions, users can model their specific scenarios and receive data-driven recommendations.

Future developments

RTX indicates that the next phase involves inverting the current process. Instead of using Maude-HCS to test existing designs, the team aims to use it to automatically generate and fine-tune HCS systems based on the model's suggestions. This would create a feedback loop where the tool not only validates designs but also proposes optimal configurations for specific use cases.

The release of Maude-HCS under an open-source license marks a significant moment in the democratization of advanced network security tools. By making this DARPA-funded technology publicly available, RTX has provided the broader research community with capabilities that were previously restricted to classified environments.

For those interested in exploring the toolkit, it is available on GitHub under the Apache 2.0 license, allowing researchers and developers to experiment with hidden communication system design without the traditional barriers of classified access or proprietary restrictions.