ARMOS 2.0: an ultra-secure commercial QKD product against PNS attacks

Commercial Quantum Key Distribution (QKD) products operating using weak coherent pulses are prone to Photon Number Splitting (PNS) attacks. Here, we present ARMOS 2.0, a commercial QKD product that is based on the Decoy-DPS QKD protocol. We can detect the PNS attack from the change in the difference of the photon-dependent yield of signal and decoy pulses. We determine the photon-dependent yield of signal and decoy pulses continuously at every cycle of 67 Milliseconds. In the scenario where the difference between the photon-dependent yield of signal and decoy pulses as well as the difference between the quantum bit error rate of the two pulses is within the tolerance value then no trace of eavesdropping is observed. The signal clicks corresponding to those scenarios are used for the generation of secure keys after undergoing the post-processing stage. We have observed that the difference between the mean photon number of the signal and decoy pulses has a direct relation to the ability to detect PNS attacks.