 This is one of the motivations for the development of quantum key distribution networks, which would route communication via alternate links in case of disruption.A quantum key distribution system may be probed by Eve by sending in bright light from the quantum channel and analyzing the back-reflections in a Trojan-horse attack.In a recent research study it has been shown that Eve discerns Bob's secret basis choice with higher than 90% probability, breaching the security of the system.