The tapping process apparently involves using so-called "intercept probes." According to two analysts I spoke to, the intelligence agencies likely gain access to the landing stations, usually with the permission of the host countries or operating companies, and use these small devices to capture the light being sent across the cable. The probe bounces the light through a prism, makes a copy of it, and turns it into binary data without disrupting the flow of the original Internet traffic.
"We believe our 3D MEMS technology -- as used by governments and various agencies -- is involved in the collection of intelligence from ... undersea fibers," said a director of business development at Glimmerglass, a government contractor that appeared, at least according to a 2010 Aviation Week article, to conduct similar types of interceptions, though it's unclear whether they took part in the British Tempora or the U.S. upstream programs. In a PowerPoint presentation, Glimmerglass once boasted that it provided "optical cyber solutions" to the intelligence community, offering the ability to monitor everything from Gmail to Facebook. "We are deployed in several countries that are using it for lawful interception. They've passed laws, publicly known, that they will monitor all international traffic for interdiction of any kind of terrorist activity."
The British publication PC Pro presented another theory: that slightly bending the cables could allow a receiver to capture their contents.
One method is to bend the cable and extract enough light to sniff out the data. "You can get these little cylindrical devices off eBay for about $1,000. You run the cable around the cylinder, causing a slight bend in cable. It will emit a certain amount of light, one or two decibels. That goes into the receiver and all that data is stolen in one or two decibels of light. Without interrupting transfer flow, you can read everything going on on an optical network," said Everett.
The loss is so small, said Everett, that anyone who notices it might attribute it to a loose connection somewhere along the line. "They wouldn't even register someone's tapping into their network," he added.
Once it's gathered, the data gets sifted. Most of it is discarded, but the filters pull out material that touches on one of the 40,000 search terms chosen by the NSA and GCHQ -- that's the content the two agencies inspect more closely.
The British anti-surveillance group Privacy International has filed a lawsuit against the U.K. government, arguing that such practices amount to "blanket surveillance" and saying that British courts do "not provide sufficiently specific or clear authorization for such wide-ranging and universal interception of communications." Their argument is that the existing surveillance laws are from the phone-tapping days and can't be applied to modern, large-scale electronic data collection.
"If their motivation is to catch terrorists, then are there less intrusive methods than spying on everyone whose traffic happens to transverse the U.K.?" said Eric King, head of research at Privacy International.
Meanwhile, the British agency, the GCHQ, has defended their practices by saying that they are merely looking for a few suspicious "needles" in a giant haystack of data, and that the techniques have allowed them to uncover terrorist plots.
If groups like Privacy International are successful, it may put an end to the capture of domestic Internet data within the U.K., but as NSA expert Matthew Aid recently told me, since 80 percent of the fiber optic data flows through the U.S., it wouldn't stop the massive surveillance operations here or in other countries -- even if the person on the sending end was British.
It's also worth noting that this type of tapping has been going on for years -- it's just that we're now newly getting worked up about it. In 2007, the New York Times thus described President Bush's expansion of electronic surveillance: "the new law allows the government to eavesdrop on those conversations without warrants -- latching on to those giant switches -- as long as the target of the government's surveillance is 'reasonably believed' to be overseas."
Want to avoid being a "target" of this "switch-latching"? A site called "Prism-break" recently released a smorgasbord of encrypted browsing, chat, and email services that supposedly allow the user to evade government scrutiny.
The only platform for which there is no encrypted alternative is Apple's iOS, a proprietary software, for which the site had this warning:
"You should not entrust neither your communications nor your data to a closed source device."