I want to talk to you about something that confused me a lot back when I first started working with EMV transactions. If you are like me, when you hear the word cryptogram, it feels like something advanced or very deep. But once I actually saw how this is used in real payment flows, I…

When I first started working on EMV transaction processing, I remember feeling completely lost looking at those cryptic acronyms such as TVR, TSI and IAC. They looked like random three-letter codes, but every time something went wrong in an EMV transaction, those were the first places I had to check. If you’ve ever debugged an…

I’ve spent a good part of my career dealing with EMV transactions. When I first got into this space, I thought EMV was just about encrypting card data and making sure the chip was harder to copy than a magnetic stripe. But the more I worked with terminals, kernels, and card profiles, the more I…

When I first started working on EMV transactions, one of the things that confused me the most was cardholder verification. I was so focused on getting the terminal to talk properly to the card, sending the right APDUs, and parsing the responses that I didn’t pay much attention to what comes next, how the system…

I want to share something with you today that brought me a lot of headaches when I was working on my first contactless EMV implementation. If you’re diving into EMV transactions, especially building or testing somethink like a SoftPOS or EMV kernel, you’ll eventually bump into a critical question: “How does the terminal know what…

When I first started working with EMV transactions, I used to wonder: what really happens the moment you tap or insert your card? On the surface it looks so simple, the card is near the terminal, something blinks, and then the screen shows “Processing”. But inside, a lot of things are happening between the card…

When I was building an EMV payment terminal for one of our retail clients a few years ago, one of the things I had to understand deeply was how the terminal figure out what application to use when a card is tapped or inserted. Sounds simple, right? Just pick one and go? Not quite. If…