Providers need the location information to efficiently route calls, but the data also reveals the whereabouts of customers, something they might not choose to support, say researchers from the University of Konstanz in Germany. They presented their research at the recent Sigcomm conference in Barcelona.
In the United States, the Department of Justice has sought permission to look at mobile-phone tracking information without a warrant.
To combat this type of surveillance, the German researchers have developed PathForge, a scheme for cell phones to swap their identities with each other until it becomes necessary to send or receive a call. The phones revert to their original identities for the duration of time they use the network, then swap them again when they are done.
To be effective, each phone would swap identities several times to make it that much harder to sort through location records to deduce the movements of a given phone.
When a call comes through for a phone, the network would try to reach the phone that holds that phone ID. At the initial contact with the network, that phone would reveal the current identification of that phone so the network can route the call to the correct handset. The network and the correct handset would authenticate to each other to make sure calls arrive at the right place.
The researchers are developing an architecture for carrying this out but don’t have a working model yet. They plan more research into getting rid of the need to reveal position at all.