iPhone keeps record of everywhere you go

The file contains the latitude and longitude of the phone's recorded coordinates along with a timestamp, meaning that anyone who stole the phone or the computer could discover details about the owner's movements using a simple program.

For some phones, there could be almost a year's worth of data stored, as the recording of data seems to have started with Apple's iOS 4 update to the phone's operating system, released in June 2010.

"Apple has made it possible for almost anybody – a jealous spouse, a private detective – with access to your phone or computer to get detailed information about where you've been," said Pete Warden, one of the researchers.

Only the iPhone records the user's location in this way, say Warden and Alasdair Allan, the data scientists who discovered the file and are presenting their findings at the Where 2.0 conference in San Francisco on Wednesday. "Alasdair has looked for similar tracking code in [Google's] Android phones and couldn't find any," said Warden. "We haven't come across any instances of other phone manufacturers doing this."

(...) Warden and Allan have set up a web page which answers questions about the file, and created a simple downloadable application to let Apple users check for themselves what location data the phone is retaining. The Guardian has confirmed that 3G-enabled devices including the iPad also retain the data and copy it to the owner's computer.

If someone were to steal an iPhone and "jailbreak" it, giving them direct access to the files it contains, they could extract the location database directly. Alternatively, anyone with direct access to a user's computer could run the application and see a visualisation of their movements. Encrypting data on the computer is one way to protect against it, though that still leaves the file on the phone.