Katharina Kohls, PhD

Assistant Professor
Radboud University, Nijmegen, NL


Open source encryption research (NCSRA III)
Open and Secure 5G Networks

Open public Internet access is an important building block of our communication. Networks like eduroam or govroam provide connectivity around the globe, however, they rely on attack-prone Wi-Fi without any kind of metadata protection. The goal of this project is to implement an open and publicly available 5G network that augments existing setups like eduroam and unleashes the security features of the new upcoming mobile generation.

Building this 5G network introduces an open and cryptographically enhanced infrastructure that otherwise is fully opaque and dominated by network operators and vendors. In contrast, our proposed network is fully decentralized and consists of voluntarily maintained access points. When contributing resources, users receive rewards through a cryptocurrency implemented in a proof-of-stake blockchain. This facilitates a growing infrastructure, and the 5G network blends in with other existing public networks.

Besides its performance features, our network concept introduces a diverse set of novel security features that clearly distinguish it from existing Wi-Fi settings and the deployments of commercial network providers. First, our network is fully decentralized and distributes the information flow among the individual voluntary resource providers. Second, we focus on a privacy-preserving deployment that minimizes the amount of sensitive and meta data. In combination, this generates a trustable network setup that is fully flexible in its deployment and can range from local 5G access over augmented campus networks to large-scale industrial contexts.

Project Call

Research Projects

Call me Maybe

Because of an implementation flaw, some LTE networks introduce a keystream reuse. An adversary can exploit this to decrypt VoLTE phone calls. All this needs is a subsequent call after the initial one. Call me maybe!


Integrity protection for user plane data is not mandatory in LTE, which introduces malleable encryption. Along with a reflection attack, an adversary can fully impersonate users in uplink and downlink direction.

Geographical Avoidance

Traffic analysis attacks against Tor are a persisting problem, and countermeasures are expensive. Instead, you can also circumvent an area you don't trust. However, things are not so easy in a decentralized system.