Using the quantum properties of single photons to exchange binary keys between two partners for subsequent encryption of secret data is an absolutely novel te- nology. Only a few years ago quantum cryptography ¿ or better Quantum Key Distribution ¿ was the domain of basic research laboratories at universities. But during the last few years things changed. Quantum Key Distribution or QKD left the laboratories and was picked up by more practical-oriented teams that worked hard to develop a practically applicable technology out of the astonishing results of basic research. One major milestone toward a QKD technology was a large research and dev- opment project funded