The secure transmission of classical information is of tremendous importance in our society, e.g., when exchanging information on finances, health, or private issues. However, the advent of quantum computing poses a serious threat to classical encryption methods. One possible solution is the use of quantum cryptography methods, either based on actual or virtual entanglement between the communicating parties. Once a Q-LAN between quantum computers is realized, the exploration of such protocols is a natural task. Among various cryptography protocols, quantum key distribution (QKD) has the most obvious application potential. Ideally, QKD exploits quantum resources for the intrinsically secure exchange of a classical key for encoding a classical message (text, music, video etc.) between partners. At WMI, we use and extend the well-established toolkit of quantum microwave technology to implement QKD schemes. Potential advantages of microwaves are high secret key rates due to large absolute bandwidths and the potential for short-distance free-space implementations. The latter promise compatibility with the existing classical microwave infrastructure and ranges comparable to that of current 5G.