WiFi has never quite been able to shake the notion that it's not the most secure technology. As we wrote last week, some super-sensitive facilities--for example, U.S. nuclear weapons labs--still do not allow the installation of WiFi networks on their grounds.

There is, however, a fool-proof way to secure your WiFi network: Turn your office or building into a Faraday cage. Geeta Dayal writes in Techworld that encasing your office or building with a thin layer of conductive material would effectively shield the RF waves that WiFi uses. Named after British physicist Michael Faraday, the Faraday cage is an implementation of the famous Gauss Law. Without getting too technical, the law asserts that in a hollow object that conducts electricity, e.g., an aluminum sphere, not only will a charge be distributed evenly across the surface of the sphere but there won't be an electric field inside of the sphere. The result is that electromagnetic fields are blocked and RF waves are shielded.

You may have already noticed the Faraday effect in every-day occurrences, like when your cell phone service is interrupted when you enter an elevator, or when your car radio's reception is disrupted when you drive through a tunnel. The U.S. government is also using the Faraday cage in response to the privacy concerns that have accompanied the introduction of RFID-enabled e-passports. These passports incorporate biometric information using RFID technology and some fear that a digital pick-pocket could walk around in an airport lounge with an RFID reader in his pocket, lifting personal information off of passports in the pockets of unsuspecting passengers. The U.S. government's response: envelope the bar code carrying the personal information in a RF-shielding layer.

Now, there are already companies selling wireless-shielding wall paper which offices can use to make themselves hack-proof. The trouble is that the same wall paper also interferes with cellular phone calls made from the office. The solution: A UK-based company is now offering wall paper that may be "calibrated" to prevent some RF waves from going through while allowing others to do so.

For more on the Faraday cage way to implement WiFi security:
- see Geeta Dayal's Techworld report