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I was recently gifted a wallet that alleges to block RFID signals. As I am sure you fine folks at Information Security are aware, this is to protect the information stored on my contactless bank card and company ID. It seems to work some of the time... I can't swipe into my office if my ID is in the wallet, but my bus pass will still scan. It's suspect!

I would like a scientific and repeatable way to test the efficacy of RFID blocking abilities of my wallet. I am looking for something beyond just testing the card at my business or on the bus, as this has been inconsistent. I am not opposed to purchasing something, but I don't know where to look nor what is sufficient.

rvictordelta
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An RFID reader system consists of an antenna connected to the proper "reader", i.e. hardware and software to process the signal received from the antenna, and then to the computer.

A simple way to test RFID blocking would be to find the frequency used by your RFID tag, buy an appropriate RFID reader and antenna, put one card at a time into your wallet, move the wallet near the antenna and check if something pops out on the reader.

For a more scientific approach, you should measure the distances at which the cards within the wallet are scanned, and compare them with the distances at which the cards outside the wallet (or better, within a non-shielded wallet having the same thickness of the shielded one) are scanned. If the two distances are almost equal, there might be something wrong with the wallet shielding.

Note that different RFID tags may use different frequencies, so you may need two different reader/antenna pairs, one for the office ID, and the other for the bus pass. In fact, the most likely reason for which the bus pass is scanned, but the office ID is not, is that they use different frequencies, and that your wallet only shields one of the two frequencies.

A. Darwin
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  • Thanks. Can you suggest a specific system that might work as a test? There are a lot of readers out there and I want to be sure I am covering all my bases. – rvictordelta Apr 07 '16 at 17:46
  • once you find the appropriate frequency, try to buy the reader with the best power output, which is usually the one with the highest antenna gain (measured in dB, dBi, etc.). If the reader or the antenna specify a given range in meters/feet, you should obviously choose the reader with the greatest range. – A. Darwin Apr 07 '16 at 17:51