The US National Security Agency has obtained a patent for a technology that can pinpoint an internet user's geographic location.
The patent covers a way to discover physical location by using a "map" of internet addresses and known locations.
The technology could let the NSA spy on internet users around the world who are looking at websites deemed to be against US national interests.
Unsurprisingly, the patent description doesn’t focus on spying. It says the technology could be used to measure the effectiveness of advertising across geographic regions or to disable passwords that were not used at “appropriate locations”.
The NSA's patented geolocation system relies on measuring the latency (the time delay) between computers exchanging data at numerous known locations on the internet, and building a "network latency topology map".
The user’s address can be identified using such a map, by measuring how long it takes known computers to connect to the unknown one.
The precision of the location found is not exact, and the system cannot be used to track users accessing the internet via dial-up connections, as the system cannot locate further than their ISP, which could be in a different place entrirely.