Steve Jobs said to the press that ‘we build a database of cell tower hotspots that could be 100 miles away from where you are, those are not telling you anything about your location.’ Yet in a written statement, Apple explained that the very same data would help your iPhone calculate its location. How can those two statements be true at the same time? Does this data indicate anything about your location or doesn’t it?
Senator Al Franken
May 10, 2011
Senators press Apple, Google for answers about location tracking
[I know! I know!
While Apple is a direct competitor to my employer (Microsoft) with this product and it’s not in my best interest to defend them I feel compelled to say that in this particular instance Apple is getting a bum rap. I worked on this same feature in Windows Phone 7 and understand the problem very, very well.
The answer given wasn’t the best and that probably made it difficult for Franken to grasp the concepts. So I’ll try again. Almost for certain this is how it works. The phone obtains a collection of cell tower locations and unique cell tower IDs in a particular geographical area. This area could be a rectangle that is 100 miles by 100 miles on a side. When the user requests their location the phone obtains the unique ID of the cell tower the phone is connected to. The ID is looked up in the collection of cell towers, just as someone’s name might be looked up in an address book. The location/address of the cell tower is then returned to the user as the best estimate of the user’s location.
As long as the cell tower IDs used for location lookup are not stored then the best that can be done by examination of the files on the phone is to see the different cell towers (and Wi-Fi) collections that were stored. As long as those collections were large (100 miles by 100 miles per collection) then the best that can be deduced is the user was someplace within that collection area. If the collection area is much smaller, say 100 feet by 100 feet (this could happen because Wi-Fi access points have much greater density that cell towers) then it becomes very important to make sure those collections are secure from snooping. If those collections are sometimes for a small geographical area and the files are not made secure then shame on Apple. They were being careless with the users privacy and should be chastised for that carelessness. But at this time I cannot conclude Apple screwed up.
So to answer Franken’s questions, those two statement can be true at the same time. The data does indicate your position within the geographical area of the hotspot locations. But that does not necessarily mean the location is know with the type of accuracy that a stalker would find particular useful–unless just knowing the city or zip code is sufficiently damaging.—Joe]