The National Security Agency most likely did not listen to you trudge to work this morning over a series of underground microphones. For all we know, the agency isn’t keeping its ears to the ground, as it were. But it could if it wanted to.
It would be the most ambitious use of what’s known as distributed acoustic sensing. Put simply, DAS systems exploit the very same fiber infrastructure that enables our day-to-day communications. But unlike the sensors and cameras baked into our phones and our computers, both tangible manifestations of the specter of surveillance, the largely untapped power (and potential abuse) of DAS is buried deep underground, virtually unseen. To think, a simple hardware add-on to existing fiber lines can have entire swaths of the telecom grid listening around the clock for anything considered physically out of the ordinary.
This is actually going on right now, albeit by a handful of private campanies specializing in both civilian and law enforcement applications of DAS technologies on land and at sea. So we should not get ahead of ourselves in presuming that Keith “I Don’t Know A Better Way to Do It” Alexander or any other NSA hacks have their ears to the ground. Indeed, of all that’s come to light from the ongoing NSA scandal, perhaps the most chilling revelation lies in the agency’s ability to eavesdrop on conversations by turning even your powered-down phone into a microphone. A sprawling network of NAS-DAS listening posts, with microphones positioned every ten meters along a fiber stretch, is probably still a pipe dream.
But the potential for an entity like the NSA to listen to you trudge to work over a series of underground mics is there. Everything is in place. Using DAS technology, the NSA might add a truly staggering number of listening devices to its global dragnet. The fiber optic cables criss-crossing the Earth, forming the central nervous system of telecommunications as we know them today, from email to texts to phone calls, are not simply the strings through which the NSA can listen to your conversations after flipping your powered-off phone into a microphone. The fiber optic cables criss-crossing the Earth are themselves a giant array of microphones, just laying in wait.