blog.sufmade.me: June 2013

What is a Faraday Shield?
https://en.wikipedia.org/wiki/Faraday_cage

Contactless Smart Cards
Singapore, being the high-tech place it is, produces lots of cards.
Membership cards, credit cards, door access cards, contactless public transport fare (ez-link) cards.
Some of the more innovative companies produce multi-purpose cards!
The result is a Frankenstein member/credit/ez-link card.

This was great at first, I survived a long time carrying a bare minimum of 2 cards to deal with life. Suddenly, I was given an extra membership club that had a lot of benefits that I wanted to carry around too.

The Problem
However, it was also an ez-link card. The problem with that is that if you hold up your wallet to an ez-link card reader on the bus or train station, it would throw an error as it detects multiple cards. With a loud series of beeps and flashing red lights. In a bunker somewhere, a monotone voice says, "The terrorists win"

Also, I didn't want to physically separate my cards, nor flip my wallet open like an FBI agent every other day (I had outgrown that phase).

Credits For The Solution
I first saw the design concept of a wallet-based Faraday shield at a Singapore Hack and Tell.

The hacker envisioned a time when evil hackers would go around touching butt pockets to scan for credit card information. So he sort of implemented it as a public/private facing wallet, depending on how he kept his wallet in his pants.

He had gone through several iterations, using aluminium foil, etc, before concluding that a soda can was the most ideal, in terms of weight, thickness and effectiveness.

The Implementation

Buy a can of soda
Drink soda
Clean can
Cut off the top and bottom of the can
Cut a straight line across the height so that you have a sheet, instead of a tube
Cut card sized pieces from the sheet