Again, it is demonstrated that the strength of your key is less important than the ease with which someone can hack some other part of your system to learn its value.
According to the researchers, quantum key distribution (QKD) implementations rely on the detectors to measure the quantum property of single photons. Using bright illumination, the team demonstrated how two commercially available QKD systems—id3110 Clavis2 and QPN 5505, developed by vendors ID Quantique and MagiQ Technologies, respectively—can be fully remote-controlled.
“This makes it possible to tracelessly acquire the full secret key; we propose an eavesdropping apparatus built from off-the-shelf components,” the team wrote. “The loophole is likely to be present in most QKD systems using avalanche photodiodes to detect single photons.”