Have blocker tags ever been commercialized?
Yes, there is. You've no doubt seen movies in which the good guys jam villains' radio communication. Well, the same principle can be applied to radio frequency identification. By emitting signals at the same frequency, you can create enough noise to make it impossible for the reader antennas to pick up the tags' signals.
Way back in 2003, when RFID was new and there was a lot of concern about privacy, RSA Security, one of the leading providers of digital security products, came up with the idea of "blocker tags" that could prevent RFID tags within the same reader field from being interrogated. These tags were designed to confuse a reader, by messing up the anti-collision algorithms designed to enable the device to communicate with one tag at a time (see RSA Security Designs RFID Blocker). The blocker tag guarantees tag collision, thereby preventing the reader from interrogating tags within the field. To my knowledge, however, blocker tags were never commercialized.
—Mark Roberti, Founder and Editor, RFID Journal
Previous Post What Tag and Reader Can Be Integrated Into a Door Lock System? »