EMV Payments
-
EMV Cryptograms Explained: ARQC, TC, and AAC Made Simple
.
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…
-
TVR, TSI and IAC: The Brains Behind EMV Logic
.
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…
-
How EMV Makes Decisions: Processing Restrictions & Terminal Action
.
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…
-
Cardholder Verification Explained: PIN, Signature, and More
.
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…
-
Reading EMV Records: How Terminals Get What They Need
.
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…
-
What Happens When You Tap or Insert? A Look at GPO and AFL
.
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…
-
How Terminals Select the Right Application on an EMV 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…
-
Best Tools to Analyze EMV Cards Like a Pro
.
When I started working on EMV projects, I thought reading data from a chip card was just about plugging it into a reader and magically the data will appear on my screen. I was wrong. The reality is that EMV cards are a little world of their own, with data stored in very specific formats,…
-
Top 25 EMV Tags You Should Know (and What They Mean)
.
Back when I was integrating a POS system for a merchant in the Philippines, one of our biggest headaches was interpreting EMV data, especially when certification time came. At first, all these TLVs looked like encrypted gibberish. But over time, they started to make sense and actually became helpful for debugging issues in the field.…
-
Offline vs Online EMV Transactions: What’s the Difference?
.
When I was working on an EMV terminal integration project for a merchant acquiring platform, one of the most confusing things for me at first was this: why do some EMV card transactions go through even if the terminal is not connected to the host? And why do others require host approval every time? It’s…