THE MOUNTING CHALLENGES
By Manuel Cereijo
On September 10, 2001, intelligence experts at the NSA intercepted two phone conversations among the millions of communications it gathers daily: "Tomorrow is zero day", and "the match begins tomorrow". The conversations originated in Afghanistan, were spoken in Arabic, and terminated in Saudi Arabia.
Such global eavesdropping is routine fare for the NSA, one of the main U.S.A. agencies doing signals intelligence, or sigint, as those in the business calls it. It is estimated to be a $2 billion a year market.
Up to a few years ago, electronic communications consisted largely of analog signals carried by wire, microwave, and satellite. To tap into these signals, sigint experts built vast radio antenna dish farms placed strategically around the globe, and deployed signal-vacuuming satellites.
Electronic traffic has become more digitized, packetized, and multiplexed, and is carried through fiber-optic cables. Optical fiber leaves no radio or magnetic signature; multiplexing has allowed tens of thousands of transmissions to be to be carried over a single line. The old sigint methods can't keep up.
However, we are managing these challenges. One way is by tampering with the opto-electronic repeaters that amplify signals over long stretches of cable. That gets to another problem: the staggering volume of raw signals data. A single transatlantic cable can carry 640 GB/s, the equivalent of 10 million simultaneous telephone calls; cables being tested now, in fact, have terabit-per second capacities.
Cleaning meaningful information from all those text and voice messages, through keyword spotting and other means, is still an immature science. Encryption poses yet another challenge. Commercial traffic routinely employs some degree of encoding, and off-the-shelf encryption products abound. Designing microprocessors and digital signal processors is another aspect of sigint.
The question now is, Who is going to do the work?
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