As the performance of quantum computers continues to increase, today’s cryptographic methods are becoming increasingly vulnerable to attacks. In telecommunications networks, established encryption methods are at risk of being compromised by quantum algorithms such as Shor’s algorithm. This threat is particularly evident in so-called ‘Store Now, Decrypt Later’ (SNDL) scenarios, in which data is currently intercepted and stored during transmission so that it can be decrypted as soon as cryptographically relevant quantum computers become available. Against this backdrop, the researchers examined in the paper how the security of future 5G and 6G core networks can be enhanced through the integration of Quantum Key Distribution (QKD).

QKD enables the secure distribution of cryptographic keys based on the principles of quantum physics. This allows eavesdropping attempts to be detected immediately and so-called man-in-the-middle attacks to be effectively prevented. This approach offers reliable protection against SNDL scenarios.

In their work, the researchers established five different convergence classes for QKD and mobile networks (ranging from over-the-top application security, through the anchoring of network identity, to trust models for the control layer) and mapped these directly onto standardised 3GPP interfaces. The Best Paper Award recognises both the scientific quality and the relevance of the research to the development of highly secure next-generation communications infrastructures.

The research is based on extensive expertise in the fields of quantum computing, quantum key distribution (QKD) and next-generation networks. For practical implementation and benchmarking, they utilised experimental environments such as:

• Open5GCore and Open6GCore integration: The proposed QKD integration frameworks utilise the flexible, software-defined core network technology of Fraunhofer FOKUS’s next-generation Open5GCore and Open6GCore architectures to test key management systems (KMS) and zero-trust key injection under real-world signalling conditions.
• Quantum computing and Eclipse Qrisp: The research team used the FOKUS testbeds as a reference for defining experimental requirements. These testbeds combine dark-fibre optical links, O-RAN fronthaul integration, precision clock synchronisation to within 100 ps (IEEE 1588v2) and ETSI GS QKD 014/015-compliant QKD hardware to evaluate service request times, key consumption rates and automated failover to post-quantum cryptography. Post-quantum encryption algorithms (such as ML-KEM) have been implemented in the quantum computing programming language ‘Eclipse Qrisp’.