Hacker's ramblings

Most of us have a credit card (or debit) for payment purposes. As I love tech, technically speaking, it is laminated polyvinyl chloride acetate (PVCA) piece of plastic conforming to ISO/IEC 7810 ID-1.
What's in a card is:

• The standard-compliant plastic frame
• ISO/IEC 7816 smart card with 8-pin connector
• ISO/IEC 14443 RFID chip and antenna for contactless payments
• (optional, deprected as insecure) ISO/IEC 7811, 7812 and 7813 compliant magnetic strip

The reason I got interested about this begun when I got a new debit card. Anybody having one of these cards know, that they do expire eventually. My bank sends me new one roughly one month before expiry, at which point I tend to destroy the old one into very small pieces to avoid some garbage digging person to be able to exploit my information.

This time, I took couple of pictures of it first (then I destroyed it) to publish in the Internet.
Waitaminute!
You're not supposed to post an image of your credit card! See https://cheezburger.com/8193250816 for a my-new-credit-card fail.

No, I'm not going to do that, instead:

Notice how couple years of usage made the card crack and laminated back and top parts of the card started peeling off. The lamination process failed somehow. Maybe the superglue wasn't super enough, or something similar. I've never seen such a thing happen before.

Here goes: I publicly posted pictures of my old debit card! Obviously, before doing that, I redacted my card number. Also, I'm not going to publish image of the back side having the CVC validation number and my signature. For those curious why I din't redact all 16 digits, the first four are not that important, because its kinda obvious the card is a Visa (first digit 4) and in Finland all Visa cards are issued by Nets Oy (formerly Luottokunta). For card numbers, see https://stevemorse.org/ssn/List_of_Bank_Identification_Numbers.html, a page rejected by Wikipedia, but resurrected from Archive.org

Points of interest in card images:

1. ISO/IEC 7816 smart card
   • All of the chip in the top slice of the card.
   • The chip is bit thicker then the top slice of the card. There is a shallow dent in the back slice to make room for the smart card chip.
2. RFID antenna for contactless payment.
   • It's EVERYWHERE! I never realized how much antenna is required to power the RFID chip.
   • If you would follow the silver antenna, it would make a very long track around the card. It will never cross. This is required to form a long loop. For those not familiar with physics and electricity, it forms a solenoid which will produce current when moving in a magnetic field (payment reader).
   • There is antenna both sides of the back-slice. Sides are connected in two points, 2 and 3.
   • Most of the antenna is around the 7816 smart card chip. That's why people are instructed to put the smart card into contactless payment terminal.
   • I think (please correct me, if I think wrong) the RFID-chip is very near the smart card chip.
3. I think (please correct me, if I think wrong) there are ten capacitors to first absorb electric current from the payment terminal magnetic field via solenoid and store it into the capacitors for the chip to do it's magic of EMV-payment. The transaction will last less then a second, so not much is needed.
4. The back-side antenna
   • Connected to front-side antenna in 2.

Bonus

If you really, really want to, you can tear your card apart and make a ring out of it:

Read all about that Man dissolves credit card to make contactless ring.