Figure 1

Time taken for a networked ID Quantique Clavis² to generate a ∼10⁵-bit shared secret across a newly established connection. Each QKD system is connected to an optical switch (introducing 1 dB of loss in each case, hence a total attenuation of 2 dB at 0 km), allowing different links to be selected. The lower bound (calculated from average secret key rates) skips device and fibre characterisation, and assumes this does not affect the performance of subsequent steps, to give the shortest possible denial of service attack duration