By Declan McCullagh
Staff Writer, CNET News.com
September 21, 2005
The National Security Agency has obtained a patent on a method of
figuring out an Internet user's geographic location.
Patent 6,947,978, 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 location."
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.
Previous Next 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 has licensed geo-location technology to
deliver location-dependent advertising, and Visa has signed 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 with
"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."
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