How can my parents protect themselves from RFID stripping?
A Faraday Cage is a special case of EM shielding. You can have shielding without grounding it. It’s not a Faraday Cage in that case, but it would do just as well for your purposes. Basically, if you do not ground the shield, it will act as a passive antenna and re-radiate the signal if it’s not a completely enclosed surface. However, the re-radiated signal will be weaker than the original, and will probably be scattered in a different direction (I’m not sure what the radiation pattern is on the RFID antennas; I assume they’re fairly directional though). You don’t need to contain the signal completely, you just need to weaken and/or scramble it up enough so that the reader can’t interpret it correctly. In a scenario where someone is trying to read the chip covertly from 20 feet away (like in the recent article about the guy doing the ‘drive-by’ passport scanning in San Francisco) it probably doesn’t take more than a few negative dB before you’ve put the signal in the noise floor. Just a
