Tag Archives: location

Friends, Romans, countrymen, lend me your consolidated.db

A big part of my thesis is going to be on extracting location information from gps, cellular radio, and wifi signals. There’s a big brou-haha in the media right now because some researchers have rediscovered [1] that iOS (the OS on the iPhone and other Apple devices) logs location information to a file called consolidated.db, which is stored indefinitely on the phone (update below). Of course, privacy folks are going berserk because this could be described as “Apple secretly tracking locations of all iPhone users”, which to me is disingenuous and tends towards fear-mongering rather than informing. I don’t think that anyone would be surprised if you told them that their iPhone has the capability of determining its location, and caching data is how applications reduce latency and bandwidth usage for network services. There’s absolutely no evidence that this data is ever shared with anyone, so it seems like it’s hardly a privacy violation, or as big a deal as people are making of it.  Also, it’s worth noting that Android logs this kind of data in the radio log and some cache files, it just doesn’t keep it around for quite as long. I read somewhere that Windows Phones cache this data as well.

The data stored in consolidated.db is very coarse location data. I have seen no evidence that the location of the phone is stored, only information about the locations of visible wifi base-stations and cell towers, which are used for triangulating the phone. Since it’s a cache, it will likely only contain a single entry for each base-station or tower, and so someone could figure out the first time you were in a specific location, but not much else (how long you were there, if and when you returned to that location, for example).

This is exactly the type of data that I’ve been hoping to collect for my research. I have an Android application that does just this, but much more frequently, and have been logging my data for almost 9 months. However, what I really intend to study is how to combine data from many people to better understand human mobility patterns, and the challenge is to actually collect this kind of data from many people. The data that I seek would include information about all the places a person visits, how long they remain there, mode of transportation, etc., and so it’s no surprise that people are hesitant to just hand over that information.

But this data would be invaluable to my research. I have approval from the Ethics Board at McGill to do this kind of research, and I can ensure that any data I collect is stored in an encrypted (secure) form, and will not be shared with anyone, not even other researchers in our group. So I’m begging the world, please send me your consolidated.db files. You’ll be helping out a poor grad student!

If you have a Mac (or Windows with python installed), and you’ve backed up your iPhone, I have a modified a script that will locate the consolidated.db file from the most recent backup and copy it to your desktop. Just run this script (it’s a python file, but the McGill web server tries to run files with .py extensions), and if it says that it found the consolidated.db file and copied it to your desktop, then please email me (jordan.frank@cs.mcgill.ca) that file. I will be forever indebted.

Update: It appears that Apple has released an update to shorten the time for which this data is cached, and also to prevent this database from being backed up in iTunes. Bummer for me, but definitely better for protecting user privacy…

[1] I first read about this in Feb. 2011, and researchers have known about this as far back as Sept., 2010 (link1, link2)