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With RFID tags increasingly used in what should be secure applications, there’s a growing market for RFID shielding devices. Wallets and pouches that block radio waves are common, and there are even instructions on how to make your own.
One of the problems in RFID shielding is that the most common shielding devices don’t block 100% of all reads, although they seriously inhibit them. Since RFID tags emit radio waves, RFID shielding is simply a subclass of electromagnetic shielding. The basic device used for electromagnetic shielding is called a Faraday cage or Faraday shield. It’s named after the scientist Michael Faraday, who first articulated the relationship between electricity and magnetism. A Faraday cage is an enclosure of conductive material. It might have holes in it, or even be completely permeated, but the holes must be no larger than the waves the Faraday cage is intended to shield. Faraday cages are imperfect, but they are also very accessible; you can improvise a Faraday shield around your RFID tags by simply wrapping them in aluminum foil. The effectiveness of the shield will also be dependent on the type of RFID tag and the strength of the reader.
If you’re concerned about your inability to completely block unwanted RFID reads, you have good reason to be. Three or five years ago, there was well-deserved uproar about easily hacked RFID credit cards. Today, if you look for RFID in the news, you see implantable credit cards. You also see RFID tags cropping up with increasing consistency in every type of conventional identification. There are RFID passports, RFID driver’s licenses, RFID school and corporate IDs. Until a better technology is found, or the gaping holes in RFID security are patched, it’s possible that the RFID tag feature on your ID may only make you easier to impersonate.