This Black Box Reads RFID Cards in Your Pocket

Started by Fred Bloggs October 18, 2021
On Wednesday, 20 October 2021 at 19:35:43 UTC+2, wrote:
> On Wed, 20 Oct 2021 00:17:41 -0700 (PDT), Wim Ton <> > wrote: > >On Wednesday, 20 October 2021 at 08:29:33 UTC+2, Jan Panteltje wrote: > >> On a sunny day (Tue, 19 Oct 2021 21:50:49 -0700) it happened Jeff Liebermann > >> <> wrote in <>: > >> >I prefer to embalm the card in aluminum foil. Unwrap the foil when > >> >the card needs to be scanned. I've done some crude testing and it > >> >seems to work quite well. > >> My plastic bank card holder I wrapped with alu foil,, then grey tape over it. > >> It prevenst the trick of people near you scanning and taken a few dollars from it, > >> possible without PIN. > > >As the video showed, reading is difficult when 2 or more cards are stacked. > >The standard allows the reader to select a single card from the stack, see for example > >but I have not seen it in the wild. > >B.t.w. A piece of copper sheet between the cards is more effective than aluminium foil. > Using something metallic to shield against 900 MHz is marginal unless > you have a totally enclosed shield, such as wrapping the card and > edges with aluminum or copper conductive foil. Building a sandwich > (stack) of alternating cards and shields still leaks quite a bit of RF > through the edges as in a slot antenna. > > What works best is an RF absorber instead of a reflector. The carbon > foam used in RF anechoic chambers is quite good, but not practical for > something carried in your pocket: > <> > -- > Jeff Liebermann > PO Box 272 > Ben Lomond CA 95005-0272 > Skype: JeffLiebermann AE6KS 831-336-2558
Payment cards, ski passes and modern passports use 13.56 MHz. The 900 MHz RFIDs I have seen in the wild were to record the time at mass running events. In the beginning, there was an idea to glue RFID payment cards as a sticker on a mobile phone. (before these supported NFC). This was a problem on iPhones with a metal backside and the reading distance from 40 mm as required by EMVCo was impossible to achieve. One trick that worked, was to glue a piece ferrite foil between the metal and the sticker. I worked for a payment terminal manufacturer in the past. One of the first to offer Paypass (Mastercard) and Paywave (Visa). An interesting project, as the standard, the test equipment and the certification were also under development at the same time.