Any cellphone can be traced by its digital fingerprint

 

Tech-savvy criminals try to evade being tracked by changing their cellphone's built-in ID code and by regularly dumping SIM cards. But engineers in Germany have discovered that the radio signal from every cellphone handset hides within it an unalterable digital fingerprint – potentially giving law enforcers a simple way of tracking the handset itself.

Developed by Jakob Hasse and colleagues at the Technical University of Dresden the tracking method exploits the tiny variations in the quality of the various electronic components inside a phone.

"The radio hardware in a cellphone consists of a collection of components like power amplifiers, oscillators and signal mixers that can all introduce radio signal inaccuracies," Hasse says. A phone's resistance, for instance, can vary between 0.1 and 20 per cent of its stated value depending on the quality of the component.

The upshot of these errors is that when analogue signals are converted into digital phone ones, the stream of data each phone broadcasts to the local mast contains error patterns that are unique to that phone's peculiar mix of components. In tests on 13 handsets in their lab, the Dresden team were able to identify the source handset with an accuracy of 97.6 per cent.

"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 says.

Their research, funded by the EU and the German government, was performed on 2G phones. But "defects are present in every radio device, so it should also be possible to do this with 3G and 4G phones," Hasse says.

The novel method is welcome but technically demanding, say forensics specialists.

"Serious criminals are extremely adept in using single-use phones and dumping SIM cards so new capabilities like this would certainly help law enforcement," says Nick Furneaux of forensics security company CSItech in Bristol, UK.

"Identifying a phone from its radio frequency fingerprint is certainly not far-fetched. It is similar to identifying a digital camera where the image metadata does not provide a serial number. From underlying imperfections in the lens, which are detectable in the image, the source camera can be identified," Furneaux says.

William Webb, CEO of the UK-based Weightless Special Interest Group , which is engineering ways to use unused TV frequencies for broadband transmission, says the method is plausible but boosting the handset recognition rate to 100 per cent will be the team's overarching challenge. "If they can't do this it could lead to hundreds of thousands of mis-tracked calls, privacy invasions and wrongly disconnected mobiles," he warns.

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6 Reasons Why Smartphones Won't Replace our minds

I noted that there's not much need tomemorize anything anymore. Ask a high-schooler today to rattle off the presidents, the periodic table or state capitals, and you'll get a blank stare—or a "Sure, let me grab my phone." Google is always available. And when's the last time you had to memorize a phone number?

But we'll never consult our phones foreverything. Some things are so important we'll have to commit them to memory even if we reach the age of universal digital retrieval. Here are a few of the life categories where memory will always beat digital lookups:

• The Frequency Factor: You access some details so often, memorization is required simply because the sheer quantity of lookups would make your life grind to a halt. Spelling, for example. Looking up every word—or directions to work each day or your school locker combination—would do a real number on your productivity.
   
• The Cultural Factor: You can't function for long in society without some basic grounding in history and culture. Without knowing these references you won't have the context to comprehend current events—or even know what you're missing or what questions to ask. You won't understand advertisements, editorials or even news articles. And you won't get anybody's jokes. You'll be unemployable and undatable.
   
• The Social Factor: You'll always have to know basic facts about your friends and family (and, of course, yourself). You should have instant access to your boss's name, your spouse's birthday and the names of your best friend's children. Fumbling to look them up electronically in a face-to-face situation would result in a lot of hurt feelings (and possibly unemployment).
   
• The Security Factor: Clearly, our gadgets can go a long way toward eliminating the need to memorize passwords. Programs like Dashlane and LastPass autofill our login information on the Web sites we visit, and even fill in our credit card information when we buy something online. But you still have to unlock those programs each day by entering a master password—one you'll have to memorize. That's true of physical security, too: you can automate parts of it, but at the end of the line, there's a physical key or card or fob. You have to know where to find it and how to use it.
   
• The Productivity Factor: Even if your daily work requires something you could easily look up, like molecular weights, stock symbols or commonly prescribed drugs, your work would bog down to a halt if you had to interrupt your flow every few minutes for a lookup. You need fluency in your own career facts to operate effectively.
   
• The Lookup Factor: Our gadgets may always be able to call up information on demand—but only if you know how and where to look for it. You still have to know how to use the tools of modern up-lookings: like Rotten Tomatoes, Wikipedia, Dictionary.com or—What's the other one? Oh, yeah—Google.
  
  

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