Bing Wang

In this work, we analyze the security of a QKD repeater chain where some, but not all, repeaters and fiber links are under the control of an adversary. We show how to bound the quantum min-entropy for this scenario, needed to compute key-rates in the finite-key scenario. Our proof methods may also have numerous applications in other areas of QKD and quantum cryptographic research. Finally we evaluate our new bound and show that positive key-rates are possible even in noisy scenarios. Since early quantum repeaters are bound to be noisy, yet also bound to be partially trustworthy in some scenarios, our work shows improved bit generation rates are possible for early QKD networks.