Very interesting stuff:
The signals produced by smartphones turn out to be so identifiable that it may never be possible to use one anonymously. Even basic privacy may be difficult to achieve.
Despite all the standardization and quality control that go into accelerometers and other sensors built into smartphones, each sensor contains enough tiny, unique imperfections to identify, not only the physical component, but also the data it records, researchers from the University of Illinois, the University of South Carolina, and Zhejiang University report.
“Even if you erase the app in the phone, or even erase and reinstall all software the fingerprint still stays inherent,” Romit Roy Choudhury, the UI associate professor of electrical engineering and computer science who led the team, said in a press release. “That’s a serious threat.”
By analyzing data from the accelerometers from more than 100 devices, the team was able to determine that tiny differences in the data recorded by the accelerometers were unique to the sensor itself, rather than reflecting flaws or differences in materials or environment from a particular plant of production line.
It’s not even necessary to get that specific or interact that much with one smartphone to identify it as unique. In June 2013, researchers at Technical University of Dresden published a paper that said variations in the performance of the power amplifiers, oscillators, signal mixers, and other components of a cellphone radio transmitter leave patterns in the analog radio signal that become a uniquely identifiable pattern of errors after the signal is converted from analog to digital.
That makes it possible to identify and track individual phones passively by their radio “fingerprints” without doing anything but listen to it, and to identify a specific phone even if the SIM card has been replaced or its unique identifying numbers have been altered, according to Jakob Hasse, lead researcher for the paper, which was presented at an ACM Workshop.
“Our method does not send anything to the mobile phones. It works completely passively and just listens to the ongoing transmissions of a mobile phone — it cannot be detected,” Hasse told New Scientist.
I forget who and when I was telling the following story to recently but it is my understanding that during the Vietnam war we had technology that could hear the radio emissions from the ignition systems from trucks many miles away. And because of variations in the ignition systems, such as worn spark plugs, dirty points, etc. the operators of that equipment learned to identify individual trucks.
I think the lesson to be learned is that if you leak electromagnetic radiation you can be tracked.