The technique works because the light in the cable propagates by bouncing off the insides of the fibre. Unsheath the cable, and a detector can pick up the tiny amount of light that escapes through the fibre's coating, explained Thomas Meier, the CEO of Swiss company Infoguard.
He demonstrated the technique on a fibre carrying a VOIP phone call over Gigabit Ethernet...
He added that the risk is not imaginary or theoretical -- optical taps have been found on police networks in the Netherlands and Germany, and the FBI investigated one discovered on Verizon's network in the U.S. Networks used by U.K. and French pharmaceutical companies have also been attacked, probably for industrial espionage, he said. (more) (more)
