  We propose a countermeasure against the so-call tailored bright illumination
attacl dor Differential-Phase-Shift QKD (DPS-QKD). By Monitoring a rate of
coincidence detection at a pair of superconducting nanowire single photon
detectors (SSPDs) which is connected at each of the output ports of Bob's
Mach-Zehnder interferometer, Alice and Bob can detect and defeat this kind of
attack.
