Instructables

Disabling Contacless Payment on Debit Cards

Picture of Disabling Contacless Payment on Debit Cards

Contactless payment is a relatively new feature in debit cards that allows you to make payments for small purchases quickly and wirelessly over a short distance without having to enter your pin.

When my old debit card expired and a new one was sent, it came with this new feature. I wanted a way to disable it since each time I was scanning my RFID access card in my wallet, the detectors at work were picking up the debit card too. They'd beep twice and sometimes get confused. Not only this, but while my bank promises it's secure, I'd rather not have a feature I don't intend to use on the off-chance that it's not.

Existing articles I found when looking for a way to disable it guess at the location or infer it by cutting apart other contactless bank cards. Since I have access to a micro-CT scanner at the University of Huddersfield Centre for Precision Technologies, I thought I'd put my card in the machine, take a 2d xray still and allow myself to find the quickest and easiest way to disable it.

The above image is a a screen grab from the Xray preview of a Nikon micro-CT scanner. The low resolution is due to it being a live view image. When in operation the micro-CT scanner is capable of a resolution of several microns.

 
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Step 1: How contactless payment works

Contactless payment works using RFID technology. A chip inside the card is powered when the card comes into close proximity to an RFID card reader. The signal emitted from the reader powers the chip though use of the embedded antenna. If this antenna is cut there will be no power to the chip and so when the card is held close to a reader the debit card won't reply.

By making cuts in the card where we know the antenna is, we can disable the wireless payment features.

Step 2: How to disable it on your card

Picture of How to disable it on your card

Make a cut 5 mm deep anywhere around the debit card or snip off a corner. This will break the antenna path and stop power to the chip when held near a reader.

That's it. Easy!

Zeugma-fr16 days ago

There is an other method, which is non-destructive.

You just have to add a small square (1cm x 1cm) of self-adhesive copper sticker on the back of the card.

Depending on where you put this copper, you will have 2 possibilities.

If you put it somewhere on the zone where the 3 spires are visible in your pic, you will scramble the RFID communication => no more communication.

If you put it in the big white zone, outside the 3 spires of the top, but inside the big spire, without covering it, you will change the antenna tuning, meaning the card will need to be closer (it need more power) to the reader to work.

adhesive copper tape : for example this :

http://www.amazon.co.uk/Direct-Products-Multi-Purp...

tofu9111 month ago
Interesting solution to a technology driven problem. Were you able to confirm card is still usable?
Jayefuu (author)  tofu9111 month ago

It does!

Gilius Jayefuu1 month ago
Does the chip still work? I live in europe and the chip is critical because all the retailers use it.

no. that's the point, basicaly. most cards chiped like this still have a magnetic strip in them (that i've seen)

people who disable the chip in this manner are doing it because they dont want their card to emit RFID. which basicaly means turning the chip off permanently.

No that is not the point. The smart card chip is different from the contactless payment feature. The smart chips have been in use for a decade in europe and nobody uses the magstrip anymore so if this solution disables the smartchip along with the contactless payment antenna then it renders the card useless in europe.

You are confusing the smart chip with the contactless payment system.

Hi Gilius,

This method does not disable the chip for contact uses (i.e. card in reader slot or in ATM). So you are safe to do it (small cut in the bottom of the card is the best way). But for some cards, this method activate a flag that basically said "card damaged": if it is the case, your bank automatically cancels it and send you a new card.

mslobogean1 month ago

Another way to get a clean picture of the traces inside of the card is to photograph it in darkness while it is backlit with a powerful light. I used my DSLR camera with the flash off-camera and behind the card instead. Around the card you need to make a sort of mask to prevent all light except what shines directly through.

Unfortunately this didn't work for me. Cutting the traces also disabled the chip, making the card useless for most purchases and in bank machines. I will need to try this again another time. Maybe there are multiple circuits and cutting them all is what killed it.

By the way, if you want to try this a hole punch works great and leaves the edges of the card smooth.

I guess I gotta be more careful with hole punches.

I've been using them for years to identify the cards (2 holes = joint account, 1 hole = sole account, etc). So far, in America we don't use the chip-n-pin system, but its coming...

Jayefuu (author)  mslobogean1 month ago

Damn! Wish I'd thought of hole punch! Mind if I add that to the last step?

Yes, of course! This is a community after all :)
pben1 month ago

I think it would be so easy to put a momentary contact switch into the antenna so that the card would be inactive until you presses on one spot on the card. This is a lazy design that leaks data to anybody with a reader that can get near your wallet. The user should have to make an active measure like pushing a button to let his data go.

domints pben1 month ago

Ummm, it won't work like this, because antenna works designed as is, and every change makes it working worse, and putting pushbutton would make antenna act as unusable piece of wire, even, when it's contacts will be connected.

Bebioeb domints1 month ago

I think what he meant was that it is a general flaw with the design of these cards, and in that case it would be easy to implement a RF switch which could disable the Antenna.

pben domints1 month ago
What I meant to say all of these card should have a manual button on them. It is just stupid to have the data available to anybody who could just get close enough with a reader.
rimar20001 month ago

Thanks for sharing, this is very interesting.

Jan_Henrik1 month ago

Thats awesome!!!

kbc21 month ago
interesting read! Thanks. not only the card readers but also the scammers who have devices to read and steal info from your card as well.