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Welcome to NearbyFriend, a research project led by Prof. Urs Hengartner.

NearbyFriend is an implementation of the Pierre protocol for becoming aware of a nearby friend, as introduced in the following paper:

Zhong, G., Goldberg, I. and Hengartner, U., Louis, Lester and Pierre: Three Protocols for Location Privacy. Proc. of Seventh Privacy Enhancing Technologies Symposium (PETS 2007), Ottawa, ON, Canada, June 2007, pp. 62-76.

Social-networking applications for mobile phones, like Buddy Beacon, Loopt, or Whrrl, exploit location technologies (e.g., GPS) that are deployed in today's cellphones to let people keep track of the location of their friends. The drawback of these existing applications is that they are bound to cellular communication and to a particular cellphone provider (Sprint and Boost in the case of Loopt, AT&T/Cingular, T-Mobile, and Verizon in the case of Buddy Beacon (as of May 2008)). So if you and your friends don't all use the same provider, you are out of luck. If the application was provided by a third party that makes it available across many cellphone providers, as in the case of Whrrl, do you really want this third party to know your and your friends' location all the time?

NearbyFriend lets you become aware of a nearby friend without being bound to a cellphone provider and without any third-party tracking. All that is required is your and your friend's cellphone (or any mobile device, such as a laptop using WiFi). NearbyFriend has your device periodically send its current location to your friend's device, which calculates the current geographic distance between the two devices. Then, the distance information is returned to your device, which will alert you if the two devices are nearby. For privacy protection, your device sends its location in encrypted form to your friend's device, and the distance computation is performed directly on the encrypted data. In other words, your friend will not be able to learn your location, and your privacy remains protected! To protect your friend's privacy, our protocol guarantees that you can learn your friend's location only if the two devices are nearby.

There are two versions of NearbyFriend, an application for the BlackBerry and a plugin for the Pidgin Instant Messaging client. The BlackBerry application is targeted at BlackBerry devices with GPS and WiFi. However, it can also use SMS for transmitting messages in case there is no WiFi coverage or if your device has no WiFi. To give the application a try on devices without GPS, you can use its demo mode, which lets you enter the coordinates of your current location manually. The implementation is entirely in Java, so it is easy to port to a different communication technology or to other smartphones (or mobile devices in general). The Pidgin plugin uses technology from Skyhook Wireless to determine the geographical location of a device. Therefore, any device that uses WiFi and that has Pidgin installed should be able to run the plugin.