Calling Bullshit On the Government's Claim That Spies Could Target the Guardian with Lasers

The Guardian office on York Way, central London. (Photo via)

This week, it was revealed that the government had sent men from their GCHQ eavesdropping agency to the Guardian's London offices. Their mission? To oversee the smashing up of a bunch of the media company's computer equipment, specifically the hard drives containing copies of the files leaked by NSA whistleblower Edward Snowden. Understandably, this has attracted a lot of attention. But perhaps the oddest snippet of information from the whole affair was a quote attributed to one of the intelligence agents that had visited Alan Rusbridger's offices.

British intelligence had apparently raised a number of concerns about the files being stored at Guardian HQ. The first was that foreign spies – from China or Russia, in particular – might hack into the Guardian's IT network and steal the files. But the Guardian explained that this would be impossible, as the files weren't stored on any kind of network or system, merely residing in isolation on individual hard drives.

After this, an "intelligence agency expert" turned up to explain why the files were still at risk. The Guardian say they were told that, "if there was a plastic cup in the room where the work was being carried out, foreign agents could train a laser on it to pick up the vibrations of what was being said". Rusbridger was also informed that "vibrations on windows [caused by people talking about the files] could similarly be monitored remotely by laser".

It’s testament to the CSI effect that most people didn’t even bat an eyelid in response to this claim. People brought up on a diet of Bond and Bourne tend to wildly overestimate the capabilities of our intelligence services. In fact, I wouldn't be surprised if claims that a functioning alcoholic in a tailored suit was capable of parking an invisible DB7 directly inside Rusbridger's office were met with a congenial response of, "Yup, that seems plausible."

But does the agent's plastic cup assertion hold any truth? Well, the physics are pretty straightforward; when we speak, we create sound waves in the air around us. When these waves impact a window, they cause it to vibrate a little. These vibrations are imperceptible to the human eye, but they can be picked up by something more sensitive, like a laser beam. In theory, a spy could stake out a position near the building, shine a laser beam at the window, pick up the reflected beam on a detector and reconstruct the original sound waves from the minute changes caused by the vibrating window.

That sounds pretty simple, and you don’t have to google very extensively to find all sorts of instructions for building laser microphone and voice extraction systems. Ben Krasnow built one in his garden, for example. “To simulate voices inside [my dining room], I used an audio commentary track off the end of a Jethro Tull album," he says, "and used a sound meter to get about 70 decibels of average volume near the window.”

Krasnow picked up sound, but the results weren’t brilliant, and his video highlights a number of problems with the technique. Double-glazing caused interference, and finding the right angle to receive the deflected beam proved difficult. When the CIA used a laser listening device to extract audio from a Russian embassy in the 1960s, they had to install a special miniature prism in an embassy window to solve the issue and redirect the laser back to the listener.

Then there are the features specific to the Guardian’s Kings Place headquarters. A spy would have to deal with noise from both an A-road that passes the building and trains arriving and departing the busy King's Cross station; a cacophony of interfering sound waves impacting the outer surfaces of the building. Then comes the real killer – a large proportion of the Guardian’s windows aren’t actually exposed to the outside world. The building has a three-layered façade along York Way – "a free-standing transparent surface made up of hundreds of slightly-curved sheets of glass". Getting a clear beam through that lot would be immensely challenging, even assuming the targets were in a room on an external wall (many of the meeting rooms aren't).

That said, laser listening devices have been accessible for decades and advances have been made in recent years. Researchers have found some success by training beams not on windows, but on the people themselves. This removes a bunch of disadvantages of the window method; windows "collect" noise from everywhere – not just the source – and intercepting the beam they reflect is fiddly. The window needs to be near the voice source.

You can judge the results of this yourself by listening to some of the .wav files they include with their paper. In one experiment they recorded a person counting by training a laser directly on the mobile phone they were using from 60 metres away. Of course, this has some problems, too – namely being able to see the target and track them with a beam.

It’s possible, if all the conditions and variables just happened to align perfectly, to imagine a secret agent using lasers to bug the Guardian, but it doesn’t seem vastly probable. Even if you could overcome the technical challenges, there are more basic things to consider: How do you even know which window to bug in the first place, or when to listen? It’s one thing to run a 24/7 operation against a Russian embassy, quite another to waste your budget gathering intel about gluten-free panzanella recipes or the latest iPad rumours. If the Bourne franchise taught us one thing, it’s that there are far easier ways for spies to get to Guardian journalists.

But then dark talk of laser beams seems more designed to impress than inform, and GCHQ’s behaviour in all this feels more like a dramatic performance than an intelligence operation. The Guardian is a global newspaper reporting on a global story with journalists based in multiple countries. Smashing a hard drive in the age of cloud computing is like deleting someone’s local Dropbox folder or Spotify cache – an inconvenient temper tantrum that serves little obvious purpose other than as an act of theatre. The lasers are just another part of the show.

Martin Robbins is a writer and talker who blogs about weird and wonderful things for the Guardian and New Statesman. Here Be Dragons is a column that explores denial, conflict and mystery at the wild fringes of science and human understanding. Find him on Twitter @mjrobbins, or email tips and feedback to martin@mjrobbins.net.

Follow Martin on Twitter: @mjrobbins

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Also – A Moron's Guide to Alan Rusbridger, Guardian Editor and Enemy of the State