The National Security Agency has obtained a patent on a method of figuring
out an Internet user's geographic location.
granted Tuesday, describes a way to discover someone's physical location
by comparing it to a "map" of Internet addresses with known locations.
The NSA did not respond Wednesday to an interview request, and the patent description
talks only generally about the technology's potential uses. It says
the geographic location of Internet users could be used to "measure the
effectiveness of advertising across geographic regions" or flag a password
that "could be noted or disabled if not used from or near the appropriate
Other applications of the geo-location
patent, invented by Stephen Huffman and Michael Reifer of Maryland,
could relate to the NSA's signals
intelligence mission--which is, bluntly put, spying on the communications
of non-U.S. citizens.
"If someone's engaged in a dialogue or frequenting a 'bad' Web
site, the NSA might want to know where they are," said Mike
Liebhold, a senior researcher at the Institute
for the Future who has studied geo-location technology. "It
wouldn't give them precision, but it would give them a clue that they could
use to narrow down the location with other intelligence methods."
The NSA's patent relies on measuring the latency, meaning the time lag between
computers exchanging data, of "numerous" locations on the Internet
and building a "network latency topology map." Then, at least in theory,
the Internet address to be identified can be looked up on the map by measuring
how long it takes known computers to connect to the unknown one.
The technique isn't foolproof. People using a dial-up connection can't be traced
beyond their Internet service provider--which could be in an different area
of the country--and it doesn't account for proxy services like Anonymizer.
Geo-location, sometimes called "geo-targeting" when used to deliver
advertising, is an increasingly attractive area for Internet businesses. DoubleClick
geo-location technology to deliver location-dependent advertising, and Visa
a deal to use the concept to identify possible credit card fraud in online
Digital Envoy holds a patent
on geo-location, and Quova,
a privately held firm in Mountain View, Calif., holds three more, one shared
"It's honestly not clear that there's anything special or technically
advanced about what they're describing," Quova Vice President Gary Jackson
said, referring to the NSA's patent. "I'd have to have our technical guys
read it, but I don't think it impacts us in any way."