August 2004


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Archive for August 6th, 2004

Stealth Wallpaper

Posted in Geekery on August 6th, 2004

Article: Stealth wallpaper keeps company secrets safe | New Scientist

I’ve always been big on security. For a couple years, I was even seriously considering starting my own business as an electronics surveilance expert. My education in electronics gives me a great understanding of this relatively simple field, and movies like Sneakers just egg me on.

Now a company in England is offering something I’ve thought about before: wallpaper that will block wireless signals in a specific spectrum. The article elaborates:

A type of wallpaper that prevents Wi-Fi signals escaping from a building without blocking mobile phone signals has been developed by a British defence contractor. The technology is designed to stop outsiders gaining access to a secure network by using Wi-Fi networks casually set up by workers at the office.

It is the work of moments for an employee to connect a paperback-sized Wi-Fi base station to a company network. That person can then wander around the office with their laptop while remaining wirelessly connected to the internet.

But it is also the work of moments then for an outsider to breach that company’s computer security using the Wi-Fi connection. Unless the Wi-Fi base station is protected by security measures that most amateur users would not bother to set up, it gives anyone up to 100 metres away the chance to bypass the corporate firewall and wirelessly hack straight into the network.

Until now, the only way to ensure people are not illicitly gaining access to company secrets has been to turn offices into a signal-proof “Faraday cage”, by lining the walls with aluminium foil, and using glass that absorbs radio waves in the windows. This ensures all electromagnetic emissions are absorbed, but it also means that no one can use a cellphone in the building.

The technolgy is simple to design, but slightly harder to manufacture – at least, it was before now. Anyone familiar with Faraday’s work knows that radio signals are waves of energy that travel in a straight line from the antenna. Each frequency has it’s own wavelength, which is described by a physical measurement. This wallpaper is designed with cross-shaped ‘holes’ designed to only allow specific wavelengths through those holes, blocking all others. Since the FCC has regulated what services can use certain wavelengths, it is a simple matter to calculate the size of hole you need to block a certain signal.

It is true that part of the WiFi spectrum is also used in some cordless phones, but this won’t be an issue, since the phone’s base station will be inside the wallpaper ‘cage’. You just won’t be able to take the phone with you when you step outside for a smoke.

At about $900 (500GBP) a square meter, however, I doubt you’ll be seeing this offered at your local home improvement store.