Your wireless footprint can help police catch a thief

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With billions of wireless devices shipped across the globe every year, it is safe to assume that most of us carry at least one wireless gadget with us much of the time. By Maxim Chernyshev

The number of wearables to be shipped this year alone is expected to exceed 100 million. Interestingly, one-third of wearables next year will be rather inconspicuous, with smart contact lenses and connected jewellery also hitting the market.

The growing demand for more traditional gadgets such as smartphones and tablets is also set to continue. The increasing popularity of wireless home automation products and smart appliances means there will be more wireless gadgets around your home.

Our cars are getting smarter too, with built-in wireless technologies delivering the latest connected driving and infotainment experience.

All in the signals

Wireless communications including the omnipresent Wi-Fi and Bluetooth technologies are underpinned by radio transmissions. These seemingly invisible radio waves travel in the open air – a medium that is easily accessible by anyone.

What cannot be seen with a naked eye can be revealed using special sensors and technology components that are getting cheaper, smaller and more capable.

Even when not actively used, a good portion of wireless devices leak radio signals that can be collected, processed and possibly even matched to a specific device.

These signals can also be labelled as digital fingerprints or wireless traces or footprints. Most wireless devices have a unique identifier such as the MAC address for Wi-Fi and BD_ADDR address for Bluetooth and these identifiers can be captured using commodity technology.

While a number of protocol improvements add privacy preservation mechanisms, research suggests that characteristics of wireless radio signals transmitted by individual devices can also be used to obtain highly unique traces.

A single wireless trace may not be very useful, but a collection of traces over time and multiple locations can be quite revealing.

There is an obvious privacy concern here, as tracking wireless devices based on their fingerprints naturally leads to tracking people. Yet, the potential benefits may outweigh these risks.

The concept of visitor analytics, for example, has gained popularity in the retail sector to provide businesses with greater visibility into the visiting habits of their stores. These analytics solutions are able to detect repeat visitors and gauge their visit duration with impressive location accuracy.

Fortunately, these solutions usually aim to incorporate privacy preservation measures and are more likely to be interested in a summary view rather than tracking of specific devices.

Similarly, a better understanding of city environments based on wireless footprints can result in more informed urban planning decisions aimed at making our cities smarter, safer and more liveable.

For example, traffic analyses based on wireless signals could be used to tackle congestion.

Theft of devices

But more importantly, wireless devices and cars are also an attractive target for burglars and car thieves.

Burglaries and theft are a growing issue in Australia. In particular, Western Australia was earlier this year labelled as the “home invasion and car theft capital” of all Australian states and territories.

Fortunately, a solution might be in sight if we consider the use of wireless traces to track and locate stolen items, provided that device fingerprints are known to the police. While voluntary MAC and BD_ADDR registrations can easily be facilitated, maintaining a database of radio signal-based fingerprints will be tricky.

But finding a stolen device could be as simple as scanning the air for its presence using a known digital fingerprint. These traces can usually be recognised from up to a 100 metres and even further away using specialised equipment.

Despite the apparent logistical and possible legal challenges, the concept has significant potential.

The idea is to disrupt the criminal network by making the use and circulation of stolen property less viable. Knowing that an unlawfully obtained laptop or a smart TV can be found could discourage people from buying or selling these items.

The solution could also reduce the claim stress faced by the insurance companies in the wake of these types of crime.

To stop the traces from being discovered, the wireless on the device would need to be turned off and in many cases this would make it useless.

With cars that have an in-dash entertainment unit with wireless technology, the unit would need to be removed or replaced and that represents additional and likely undesirable effort.

Practical attempts to leverage wireless traces for law enforcement are already taking place. A proof-of-concept solution called L8NT (“latent”) that uses Wi-Fi has been on trial in the US state of Iowa late last year.

While the concept is simple and the underlying technology is readily accessible, there will be significant challenges to overcome.

To be effective, the solution will require a widespread sensor network and integration of additional technology into the police cars, public transport and city infrastructure. Drones can also be used to fly sensors up in the air for increased coverage.

Certain types of wireless footprints can also be easily spoofed on some devices and techie criminals will likely learn and use tricks to effectively hide these devices. But, it is unlikely that an average home burglar will have the necessary technical skills to use these techniques.

The Conversation

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