WHAT IS IT?
RFID (Radio Frequency Identification) tags are small computer chips attached to an antenna. When pinged by a reader device (also called an interrogator device, to make it sound scary), the RFID tag broadcasts whatever information it has been programmed with. This information can be as simple as a short string of numbers (like the numbers at the bottom of a bar code or a credit card number) or as complex as photos and packets of encrypted data.
The transmission range of an RFID chip is limited by the power source of the chip and the size of the antenna. The most common ones are thick labels with a strip of conductive material running like a maze around a tiny chip in the middle. If you bought this book at a major retailer or got it in a library, there might be one stuck to the inside cover. Check it out. I’ll wait.
The smallest RFID chips are roughly the size of a speck of dust—small and light enough to float on the convection currents in a sunbeam like a cat hair. At such diminutive sizes, it is difficult to attach an antenna—limiting transmission range to only a few millimeters—and information storage is limited to a short string of numbers, but technology improves constantly.
Organizations from libraries to hospitals to armies to grocery stores use this technology for inventory tracking. The United States, European Union, and a number of other countries have embedded them in passports to ease immigration control. Cell phone manufacturers include programmable versions in their devices to allow you to link your phone to your bank account or credit cards. If you drive regularly on toll roads, you probably have one—in the form of a small plastic box—stuck to the inside of your windshield. You might have several in your wallet, masquerading as a workplace key card, library card, credit card, or subway fare card.
Many of these tags carry harmless data in the form of stored value without any personally identifying information—as in the case of your subway fare card or the FastPass in your car. But most of them carry at least some sensitive information. Every tag is unique, meaning that even the innocuous ones can be used to track you.
With the increasing ubiquity of RFID tags, each of us sacrifices more and more locational privacy. Soon our wallets, clothing, and key rings will be bursting with easily tracked radio signatures. The stores we shop at, the companies whose brands we buy, our employers, and our government will all be keeping an eye on our location and habits.