[LINK] refusing contactless cards - RFID shielding

[Robin Whittle]

Hi Brendan,

You wrote, in part:

> Tin foil card wallet?
> 
> Craft knife on the rfid chip?

There seems to be no separate RFID chip on the contactless cards I have
here.  However, there is an embedded multi-turn wire coil/antenna around
the edge of the card - this is visible in the slightly translucent
Commonwealth Bank card.  A single scissor cut of 6mm into the card
anywhere around the edge would disable the RFID functions of the card.
Probably a cut with a knife to the top surface would do the trick too,
since the wires seem to be near the top surface.

Perhaps this would be prohibited by anti-tampering aspects of the
contract.  If so, perhaps it could later be argued that the card met
with an unfortunate accident . . .   Best not try this with an RFID
passport.

Googling:

  foil RFID credit card

turns up lots of instructions for shielding, including:

  http://www.cryptalloy.net/en/

which is a purpose-built RFID sheilding foil intended to be incorporated
into products such as wallets and purses.

Without special equipment, how could we to test such shielding without
actually waving the shielded card near an RFID card terminal which was
primed to charge our account.  RFID readers might vary greatly in
sensitivity, and we might assume that a crowd-wandering RFID electronic
pickpocket (if such things are possible, I haven't properly researched
it) might have a reader with an unusually strong field to energise
shielded cards, with a matching highly sensitive amplifier to pick up
the weaker response signals which escape the shielding.

  - Robin