Your location info is too revealing: data boffins A group of researchers partly supported by SAP has taken a look at one of the big problems with so-called “anonymised” data: the way spatial correlations in mobile data can be used to re-identify individuals in large data sets. Location data is the big problem, the Singapore-led group says: even if the resolution of a phone's …
2006: A Face Is Exposed for AOL Searcher No. 4417749
http://www.nytimes.com/2006/08/09/technology/09aol.html?pagewanted=all&_r=0
PS: I am almost sure an identical incident with Google publishing data for research purpose. Either my memory is broken or crooked by Google.
Historically the clueful knew you shouldn't send anything you didn't want at least a dozen total strangers to see.
Today you don' want people knowing where you are.
Switch it on for when you're places you want people to know you are.
Switch it off the rest of the time.
Today you don' want people knowing where you are.
Can't say I'm all that bothered. But if you're that paranoid you'd best be unemployed and homeless then. Anyone with a full-time job and permanent place of resident can be found by the authorities almost any time they want you.
"Anyone with a full-time job and permanent place of resident can be found ..."
It's not about knowing where to look if they want to find you at work or at home. Anybody, with the right information, can do that and many people know where you work and where you live and you're certain to have voluntarily and knowingly given this information to many people.
This identifcation from partial location trajectory data means that your other movements and locations can be identified as being yours. Today, the police can get this information (with the appropriate authorisation), presumably for good reasons. Soon, any advertising Tom, Dick or Harriet will be able to find out where you were at what time; unless further fragmentation of the trajectory is mandated.
It's not about the authorities being able to find you, it's about the authorities banging on your door demanding to know why you spent 35 minutes last week in the same general space-time vicinity as some guy they decided yesterday was a terrrist and you never even knew existed.
And I mean that literally. I always thought this obvious, even just the less accurate cell tower locations would identify the source given enough data. It's like taking the limit of a function that refines itself and does it quickly enough that only a few data points are required. Here the tower derived data points are an arbitrary randomization of GPS accurate data. Further, I'm sure that replacing data in that field doesn't really address the problem. The mere existence of data points there probably can be correlated to a particular user. [Those data points will be correlated with the internal state of the RNG which leads to all sorts of possibilities.] To be truly safe, you delete the field(s) entirely and even then there will still be information useful in de-anonymousizing the source as cited above.
In any case, I wonder how much of the nature of the research correlates with 'nature' of Singapore. I liked the place but authoritarian regimes don't bother me, personally. They do offend my libertarian nature.
If you reduce resolution to "what cell tower are you connected to?" you narrow down where everyone lives within a range of a single cell tower by seeing where their phone typically spends the night. You can further reduce them to "where they live and where they work" pairs by seeing where their phone typically spends weekdays.
With those two steps alone given those two data points you can probably narrow down most to a few dozen candidates, some already to a single candidate. Add a third location for hours aside from home/work, like their favorite pub, their girlfriend's address, their favorite fishing hole or whatever and you can probably narrow down to a single candidate in the majority of cases with only three known cell tower locations!
Now add tracking for others who live with you, like your wife and her place of work, your kids and where they go to school, etc. and any family is probably super easy to identify. Good thing the cellular companies don't provide cell tower location information to the NSA to save forever.
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