ASSI
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EMV Made Simple: What It Is and Why It Matters
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This post is the starting point of a full-blown series consisting of around 45 blog posts that will explore the entire EMV payment ecosystem from the fundamentals to advanced cryptographic operations, issuer scripts, and even certification. If you’ve been meaning to truly understand EMV, you’re in the right place. This is not a one-off explainer…
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Understanding Data Types in ISO 8583
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Back when I was working on a host emulator project for issuer and acquirer simulations, one of the tricky areas I faced early on was understanding how the data elements in ISO 8583 are formatted. It wasn’t just about packing and unpacking the messages, the real challenge was knowing how to interpret the field types…
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Decoding ISO 8583: Understanding HEX, Decimal, Binary, and ASCII Formats
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Hello everyone! In this post, I want to share something that recently became a big part of one of my projects, decoding and understanding different encoding formats used in ISO 8583 messages. If you have worked with payment switching, host simulations, or POS terminal development, you know how important it is to be comfortable with…
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Breaking Down ISO 8583 Data Elements
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In my previous blog post, I already discussed a high-level overview of ISO 8583 Data Elements. If you haven’t read it yet, I highly recommend checking it out first, as this current post will build on some of those concepts without going into the same level of detail—to keep this article focused and concise. Understanding…
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High-Risk Merchants and Rolling Reserves: Everything You Need to Know
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If you’ve been navigating the world of payment processing, you’ve probably heard the terms “high-risk merchant” and “rolling reserves” thrown around a lot. It can be a bit overwhelming to figure out what these mean and how they affect your business. Don’t worry, I’ve been there too, and I’m here to break it down for…
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Understanding Chargebacks in the Payment Industry: A Complete Guide for Merchants
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If you’re in the payment industry or running a business that processes credit card payments, you’ve probably encountered chargebacks. They can feel like a nightmare lost revenue, processing fees, and the frustrating feeling of dealing with something out of your control. Having spent a good chunk of my career in payment systems, I’ve faced my…
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ISO 8583: Message Structure
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If you’ve ever worked on a payment switch, POS terminal integration, or bank-to-bank transaction processing, you’ve probably encountered the mysterious and often misunderstood beast known as ISO 8583. When I first touched it in one of our payment switch projects, I remember being confused by TPDU headers, LLVAR fields, and different message formats. It felt…
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ISO-8583: Understanding Message Type Indicator
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Hey there! If you’ve ever worked with payment systems, especially in the realm of financial transactions, you’ve probably encountered ISO 8583. This standard is the foundation for electronic transactions across ATMs, POS terminals, and online payment gateway. One of the core components of ISO 8583 is the Message Type Indicator (MTI). It’s a four-digit code…
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ISO-8583: Understanding Data Elements
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If you’ve ever worked with payment processing, especially in integrating POS terminals, ATM transactions, or online payment gateways, you’ve probably encountered ISO-8583. It’s that cryptic-looking standard that governs financial transactions across the world. When I first dealt with ISO-8583 in one of my payment integration projects, I remember thinking, “Why does this feel like decoding an ancient manuscript?”…
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Fundamentals of PCI-SSF: What you Need to Know
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If you’ve ever worked on payment systems, security compliance probably haunts you in your sleep. PCI DSS, 3D Secure, tokenization—there’s always some new acronym to tackle. One of the newer kids on the block is PCI-SSF (Payment Card Industry Software Security Framework), and if you’re dealing with POS systems, payment gateways, or even SoftPOS, this…