Entries Tagged "geolocation"

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Dumb Risk of the Day

Geotagged images of children:

Joanne Kuzma of the University of Worcester, England, has analyzed photos that clearly show children’s faces on the photo sharing site Flickr. She found that a significant proportion of those analyzed were geotagged and a large number of those were associated with 50 of the more expensive residential zip codes in the USA.

The location information could possibly be used to locate a child’s home or other location based on information publicly available on Flickr,” explains Kuzma. “Publishing geolocation data raises concerns about privacy and security of children when such personalized information is available to internet users who may have dubious reasons for accessing this data.”

It’s children, though, so it’s going to be hard to have a rational risk discussion about this topic.

Posted on February 15, 2012 at 1:11 PM • View Comments

Pinpointing a Computer to Within 690 Meters

This is impressive, and scary:

Every computer connected to the web has an internet protocol (IP) address, but there is no simple way to map this to a physical location. The current best system can be out by as much as 35 kilometres.

Now, Yong Wang, a computer scientist at the University of Electronic Science and Technology of China in Chengdu, and colleagues at Northwestern University in Evanston, Illinois, have used businesses and universities as landmarks to achieve much higher accuracy.

These organisations often host their websites on servers kept on their premises, meaning the servers’ IP addresses are tied to their physical location. Wang’s team used Google Maps to find both the web and physical addresses of such organisations, providing them with around 76,000 landmarks. By comparison, most other geolocation methods only use a few hundred landmarks specifically set up for the purpose.

The new method zooms in through three stages to locate a target computer. The first stage measures the time it takes to send a data packet to the target and converts it into a distance—a common geolocation technique that narrows the target’s possible location to a radius of around 200 kilometres.

Wang and colleagues then send data packets to the known Google Maps landmark servers in this large area to find which routers they pass through. When a landmark machine and the target computer have shared a router, the researchers can compare how long a packet takes to reach each machine from the router; converted into an estimate of distance, this time difference narrows the search down further. “We shrink the size of the area where the target potentially is,” explains Wang.

Finally, they repeat the landmark search at this more fine-grained level: comparing delay times once more, they establish which landmark server is closest to the target. The result can never be entirely accurate, but it’s much better than trying to determine a location by converting the initial delay into a distance or the next best IP-based method. On average their method gets to within 690 metres of the target and can be as close as 100 metres—good enough to identify the target computer’s location to within a few streets.

Posted on April 8, 2011 at 6:22 AM • View Comments

Sprint Provides U.S. Law Enforcement with Cell Phone Customer Location Data

Wired summarizes research by Christopher Soghoian:

Sprint Nextel provided law enforcement agencies with customer location data more than 8 million times between September 2008 and October 2009, according to a company manager who disclosed the statistic at a non-public interception and wiretapping conference in October.

The manager also revealed the existence of a previously undisclosed web portal that Sprint provides law enforcement to conduct automated “pings” to track users. Through the website, authorized agents can type in a mobile phone number and obtain global positioning system (GPS) coordinates of the phone.

From Soghoian’s blog:

Sprint Nextel provided law enforcement agencies with its customers’ (GPS) location information over 8 million times between September 2008 and October 2009. This massive disclosure of sensitive customer information was made possible due to the roll-out by Sprint of a new, special web portal for law enforcement officers.

The evidence documenting this surveillance program comes in the form of an audio recording of Sprint’s Manager of Electronic Surveillance, who described it during a panel discussion at a wiretapping and interception industry conference, held in Washington DC in October of 2009.

It is unclear if Federal law enforcement agencies’ extensive collection of geolocation data should have been disclosed to Congress pursuant to a 1999 law that requires the publication of certain surveillance statistics—since the Department of Justice simply ignores the law, and has not provided the legally mandated reports to Congress since 2004.

Sprint denies this; details in the Wired article. The odds of us ever learning the truth are probably very low.

Posted on December 3, 2009 at 7:18 AM • View Comments

Best Buy Sells Surveillance Tracker

Only $99.99:

Keep tabs on your child at all times with this small but sophisticated device that combines GPS and cellular technology to provide you with real-time location updates. The small and lightweight Little Buddy transmitter fits easily into a backpack, lunchbox or other receptacle, making it easy for your child to carry so you can check his or her location at any time using a smartphone or computer. Customizable safety checks allow you to establish specific times and locations where your child is supposed to be—for example, in school—causing the device to alert you with a text message if your child leaves the designated area during that time. Additional real-time alerts let you know when the device’s battery is running low so you can take steps to ensure your monitoring isn’t interrupted.

Presumably it can also be used to track people who aren’t your kids.

EDITED TO ADD (11/12): You can also use an iPhone as a tracking device.

Posted on October 28, 2009 at 1:28 PM • View Comments

Inferring Friendship from Location Data

Interesting:

For nine months, Eagle’s team recorded data from the phones of 94 students and staff at MIT. By using blue-tooth technology and phone masts, they could monitor the movements of the participants, as well as their phone calls. Their main goal with this preliminary study was to compare data collected from the phones with subjective self-report data collected through traditional survey methodology.

The participants were asked to estimate their average spatial proximity to the other participants, whether they were close friends, and to indicate how satisfied they were at work.

Some intriguing findings emerged. For example, the researchers could predict with around 95 per cent accuracy who was friends with whom by looking at how much time participants spent with each other during key periods, such as Saturday nights.

According to the abstract:

Data collected from mobile phones have the potential to provide insight into the relational dynamics of individuals. This paper compares observational data from mobile phones with standard self-report survey data. We find that the information from these two data sources is overlapping but distinct. For example, self-reports of physical proximity deviate from mobile phone records depending on the recency and salience of the interactions. We also demonstrate that it is possible to accurately infer 95% of friendships based on the observational data alone, where friend dyads demonstrate distinctive temporal and spatial patterns in their physical proximity and calling patterns. These behavioral patterns, in turn, allow the prediction of individual-level outcomes such as job satisfaction.

We all leave data shadows everywhere we go, and maintaining privacy is very hard. Here’s the EFF writing about locational privacy.

EDITED TO ADD (10/12): More information.

Posted on September 21, 2009 at 1:41 PM • View Comments

EFF on Locational Privacy

Excellent paper: “On Locational Privacy, and How to Avoid Losing it Forever.”

Some threats to locational privacy are overt: it’s evident how cameras backed by face-recognition software could be misused to track people and record their movements. In this document, we’re primarily concerned with threats to locational privacy that arise as a hidden side-effect of clearly useful location-based services.

We can’t stop the cascade of new location-based digital services. Nor would we want to—the benefits they offer are impressive. What urgently needs to change is that these systems need to be built with privacy as part of their original design. We can’t afford to have pervasive surveillance technology built into our electronic civic infrastructure by accident. We have the opportunity now to ensure that these dangers are averted.

Our contention is that the easiest and best solution to the locational privacy problem is to build systems which don’t collect the data in the first place. This sounds like an impossible requirement (how do we tell you when your friends are nearby without knowing where you and your friends are?) but in fact as we discuss below it is a reasonable objective that can be achieved with modern cryptographic techniques.

Modern cryptography actually allows civic data processing systems to be designed with a whole spectrum of privacy policies: ranging from complete anonymity to limited anonymity to support law enforcement. But we need to ensure that systems aren’t being built right at the zero-privacy, everything-is-recorded end of that spectrum, simply because that’s the path of easiest implementation.

I’ve already written about wholesale surveillance.

Posted on August 14, 2009 at 6:30 AM • View Comments

On the Anonymity of Home/Work Location Pairs

Interesting:

Philippe Golle and Kurt Partridge of PARC have a cute paper on the anonymity of geo-location data. They analyze data from the U.S. Census and show that for the average person, knowing their approximate home and work locations—to a block level—identifies them uniquely.

Even if we look at the much coarser granularity of a census tract—tracts correspond roughly to ZIP codes; there are on average 1,500 people per census tract—for the average person, there are only around 20 other people who share the same home and work location. There’s more: 5% of people are uniquely identified by their home and work locations even if it is known only at the census tract level. One reason for this is that people who live and work in very different areas (say, different counties) are much more easily identifiable, as one might expect.

“On the Anonymity of Home/Work Location Pairs,” by Philippe Golle and Kurt Partridge:

Abstract:

Many applications benefit from user location data, but location data raises privacy concerns. Anonymization can protect privacy, but identities can sometimes be inferred from supposedly anonymous data. This paper studies a new attack on the anonymity of location data. We show that if the approximate locations of an individual’s home and workplace can both be deduced from a location trace, then the median size of the individual’s anonymity set in the U.S. working population is 1, 21 and 34,980, for locations known at the granularity of a census block, census track and county respectively. The location data of people who live and work in different regions can be re-identified even more easily. Our results show that the threat of re-identification for location data is much greater when the individual’s home and work locations can both be deduced from the data. To preserve anonymity, we offer guidance for obfuscating location traces before they are disclosed.

This is all very troubling, given the number of location-based services springing up and the number of databases that are collecting location data.

Posted on May 21, 2009 at 6:15 AM • View Comments

No Warrant Required for GPS Tracking

At least, according to a Wisconsin appeals court ruling:

As the law currently stands, the court said police can mount GPS on cars to track people without violating their constitutional rights—even if the drivers aren’t suspects.

Officers do not need to get warrants beforehand because GPS tracking does not involve a search or a seizure, Judge Paul Lundsten wrote for the unanimous three-judge panel based in Madison.

That means “police are seemingly free to secretly track anyone’s public movements with a GPS device,” he wrote.

The court wants the legislature to fix it:

However, the District 4 Court of Appeals said it was “more than a little troubled” by that conclusion and asked Wisconsin lawmakers to regulate GPS use to protect against abuse by police and private individuals.

I think the odds of that happening are approximately zero.

Posted on May 15, 2009 at 6:30 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.