The SATURN project addresses critical security challenges in Quantum Key Distribution Networks (QKDN). With the development of quantum computers, the threat to classical cryptography is growing, making quantum-safe alternatives essential. Particularly critical are ‘harvest now, decrypt later’ attacks, where encrypted data is stored today to be decrypted later by quantum computers. While QKD enables secure key exchange from an information-theoretic point of view, its practical implementation in networks poses major challenges. Current QKD modules over optical fibre are limited to distances of about 150 km. For longer distances, intermediate nodes must be used, which raises new security issues.
The SATURN project will develop secure and efficient protocols for key forwarding in QKDNs. A hybrid approach will be pursued, combining QKD with post-quantum cryptography (PQC). Existing protocols will be formally analysed, new security models will be developed, and practical implementation guidelines will be produced. The results should provide an informed decision-making framework for the use of QKDNs, taking into account both security and practical aspects such as performance, scalability and crypto-agility.
