Like many of you I’ve been tracking all the “hub bub” about Pete Warden and Allisdair Allen’s iPhone location exploit. There has been not only sensationalist media hype, but also claims of this being old news. Having been a victim of media hype and not particularly having any privacy concerns around my iPhone – I liberated my iPhone location data (ok Justin actually did it) and uploaded it to GeoCommons. Seeing my tracks was pretty cool, but you can do that with Pete and Allisdairs clever package out of the box.
I wanted to investigate how much of my privacy was actually revealed by the data. My conclusion – not much. I think we all inherently understand how much the media sensationalizes stories, but I thought it would be useful to document how much privacy this data actually reveals. Let’s start with a map of all my locations:
This shows my general travel patters – live in Washington DC and I travel to California, Colorado and New York and good amount. No big surprises there, although it is a bit tough to tell what places I was at most often from the piles of points on top of each other. So, I ran a quick aggregation to US counties and generated this map.
Now I can see the counts by counties for the places my iPhone has traveled. This allows me to quantity my frequency to different location, and has the added benefit of obscuring the exact locations I went. Living in the DC metro area I wanted to get more detail of my patterns locally so I aggregated the data to zipcodes and generated this map:
This gave my a better local context, but also showed something odd. The zip code where I apparently spend the most time is 22202 in south Arlington where I rarely go unless I’m flying out of DCA. This was curious, so I went a level deeper and aggregated the data to Census block groups and generated this map:
The map does confirm that DCA airport is the area that had the highest number of locations stored by my iPhone, but the really weird part is where I live and work did not show up as an active location. This was further reinforced when I went back the point data as seen in the map below:
There are no points closely associated with my house or my place of work. Adding to the oddness the iPhone “location data” places me in locations I’ve never been.
This may surprise some of you but I’ve never actually been inside the Pentagon. Why the stark deviation from places I know I’ve been with my iPhone very frequently and places I’ve never been with my iPhone? The answer lies in the fact the iPhone is storing cell phone tower triangulations not GPS coordinates. Others have said this previously although some have erroneously said the data is just showing the location of cell phone towers. To demonstrate this I added FCC cell tower locations to my iPhone location log data.
Last fall I went surfing in Santa Cruz, but I did not take my iPhone with me in my wetsuit So, how do we get a location for me out in the Pacific Ocean below:
When we add the cell tower locations and draw a simple triangle the odd locations begin to make a bit more sense. Although I’m not sure why airports create such a massive amount of location logging by the iPhone. When I went back to my county aggregation map and added airports the correlation was exceedingly high. Maybe it is the density of phones and the amount of movement causing frequent cell tower hands offs for signal, and those all get logged by the phone? This would also explain why I’m not getting lots of activity near my home. The phone is logging when I switch between two cell coverage areas only. There are probably not a lot of hand offs between my work and home since they are quite close to each other. Not sure but would love to hear some theories.
Not surprisingly the amount of private information you’ll learn of me from this post is pretty scant. More than likely you would infer a lot of very inaccurate things about me, none of which include where I live or where I work. You’ll learn a whole lot more interrogating my Twitter or Foursquare feed. In many ways this is the only salient point - I gave permission to Twitter and Foursquare to track my location but not knowingly to Apple. I say knowingly because who the hell knows what is in the 55 page ToS I have to agree to every time I download a new iPhone app. My conclusion there is not much to fear from a privacy perspective but it certainly makes me trust Apple less and less.
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