MuQuaNet - Applying quantum-secure communications to space operations

Abstract

The development towards fault tolerant quantum computers has accelerated in recent years. It is therefore, reasonable to posit that quantum computers will be able to solve numerical problems previously unsolvable in a reasonable amount of time. This is particularly relevant in the context of factoring large composite numbers and solving the discrete logarithm problem. These two mathematical problems form the foundation for the vast majority of asymmetric encryption systems and key exchange procedures (such as RSA, DH, ECDH, ECDSA, and so forth). It is anticipated that quantum computers with cryptographic capabilities will become available within the next one or two decades. A significant number of high-security applications require the encryption of classified material beyond this timeframe. Consequently, the mitigation of the threats posed by quantum computers to classical encryption schemes has become a race against time, already. Currently two approaches are discussed to ensure quantum secure encryption and communications after the breakthrough of quantum computers. The first approach is called Post-Quantum-Cryptography (PQC). Here, new encryption and signature schemes are implemented based on mathematical problems which are hard to crack classically and by quantum computers. The second approach is based on a secure exchange of encryption keys and is referred to as Quantum Key Distribution (QKD). This approach utilizes the quantum mechanical properties of photons in a way that enables the sending and receiving parties to detect any attempts by an eavesdropper to record or alter the transmitted keys. If the successfully transferred keys are used only once for encryption unconditional security can be achieved in theory. Nevertheless, quantum key distribution (QKD) requires either dedicated fiber-optic lines that are solely used for the key exchange, commonly referred to as a dark fiber network or free-space links, which utilize a laser terminal and a telescope as the sender and receiver, respectively. Free-space links can be employed for mobile applications that facilitate quantum-secured communication with minimal deployment times over distances of several kilometers. Moreover, free-space links are utilized to exchange quantum keys between optical ground stations (OGS) and QKD satellites. By leveraging the in-orbit deployment of quantum keys, QKD enables the establishment of secure long- distance connections. DLR (Deutsches Luft- und Raumfahrtzentrum) is part of the Munich Quantum Network (MuQuaNet), which is a research dark fiber network situated in the metropolitan area of Munich. The project is spearheaded by the University of the Bundeswehr (Munich) and is operated in conjunction with a number of other research facilities and governmental institutions. The QKD network is comprised of multi-vendor QKD devices, including both prepare-and-measure and entanglement-based systems. DLR, in particular the German Space Operation Center (GSOC) assumed the task of demonstrating the use case of encrypting the ground segment for satellite operations employing QKD. This presentation will provide an overview of the current status of our work, including a technical explanation of the implementation and a general description of the approach used to encrypt part of our TMTC data streams as part of this QKD experiment.