Device calibration impacts security of quantum key distribution.
Characterizing the physical channel and calibrating the cryptosystem hardware are prerequisites for establishing a quantum channel for quantum key distribution (QKD). Moreover, an inappropriately implemented calibration routine can open a fatal security loophole. We propose and experimentally demonstrate a method to induce a large temporal detector efficiency mismatch in a commercial QKD system by deceiving a channel length calibration routine. We then devise an optimal and realistic strategy using faked states to break the security of the cryptosystem. A fix for this loophole is also suggested.
Max Planck Institute for the Science of Light, Günther-Scharowsky-Straße 1, Bau 24, 91058 Erlangen, Germany. nitin.jain@mpl.mpg.de
Nitin
N
Jain
Christoffer
C
Wittmann
Lars
L
Lydersen
Carlos
C
Wiechers
Dominique
D
Elser
Christoph
C
Marquardt
Vadim
V
Makarov
Gerd
G
Leuchs