Satellite-based Quantum Key Distribution Using Trusted and Untrusted Satellite Nodes
András Mihály, László Bacsárdi
Budapest University of Technology and Economics
Today's safe communication mostly depends on the fact that the public key-based cryptography is hard to break using classical computers. Which is true since even for today's most powerful computers, it would take decades to decipher this type of encoding. But for nonconventional computers, e.g., a quantum computer, this process would only take seconds.
At the same time, using symmetrical-key-based cryptography can still provide us with the necessary amount of security in the world of universal quantum computers. The only question is what kind of platforms we can use to securely generate or distributes the necessary keys. This can be done by using a quantum key distribution (QKD) protocol which is simple and well-functioning, but essentially it works point-to-point. When we interconnect multiple QKD systems, we start to talk about quantum internet. These are systems that not only are able to generate keys using quantum bits but can transport quantum information using fiber or free-space links.
During our work, we simulated satellite-based QKD systems. We simulated a system that connects two points on the Earth using sets of satellites. In these simulations, we examined the possibility of instead fiber connections (which is expensive to build), using a series of satellites.