, 11 tweets, 4 min read
Ever wondered what lies beneath that cool looking chip on your bank card? What does it do? Why is it there?
Well here's a little pointless thread that delves into the magic using my @monzo card as an example
Firstly, the chip is called an EMV chip, where E is Europay, M is Mastercard and V is, you guessed it, Visa. en.wikipedia.org/wiki/EMV
The specifications for the chip were published in 1996. The Fugees "Killing Me Softly with His Song", was really popular too
This chip is actually a really powerful computer. It helps with cryptographic processing (payments) and can store data. It works when you touch it against a contactless reader using Near-field communication (NFC), or inserting it into a device (old skool baby)
The above is specified by two standards:

ISO/IEC 7816: Identification Cards –Integrated Circuit(s) Cards
ISO/IEC 14443: Identification Cards –Contactless Integrated Circuit(s)Cards –Proximity Cards
Sadly these standards cost a fortune to read, which is counterproductive. Standards should be open to all, not only to those who can afford them.
On the Integrated Circuit (IC), you'll find a Smart Card Operating System (COS) and is a micro operating system. For the electronic enthusiasts out there, this is how the pins look.
So what happens when you tap your card or plug it in? Well this is something that always interested me when buying coffee and the flow is as follows:

1: Activation (turn it on)
2: Exchange info
3: Deactivation (turn it off)
Activation is cool as it applies power to boot the chip up using a minimum value of 1 MHz and max value of 5 MHz and looks like this
for step 2, the chip uses Application Protocol Data Unit (APDU) to send data. Ivan Buetler did a brilliant talk in 2008 at @blackhat on this protocol blackhat.com/presentations/…
So what does this super computer look like? Well here's an X-ray of my @monzo card.
You can see the coils of wire used to produce electromagnetic waves, which can then be picked up and turned back into current by a another coil of wire. You can also see the bonding wires.
I appreciate this is all rather nerdy and pointless, but a lot of work is going into what the next generation of EMV chips look like, as our payment methods change. It's a pretty exciting time when it comes to payments and contactless.
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