Search
35 articles found
Merchant & POS
In the first post I explained what closed-loop payment systems are and how they differ from open-loop ones. Many of the replies I received boiled down to one question: how do these systems actually work behind the scenes once a QR code is scanned?
ISO 8583
F34 — Primary Account Number, Extended: this field is filled when the card number cannot be placed in F2 because it is longer than 19 digits or contains special characters.
Payment Systems
The Hidden Side of the Payments World. The words a person working in the payment systems industry hears most over a career are probably Visa, Mastercard, POS, debit card, virtual POS, acquiring and card issuing. Frankly, my own career did not unfold very differently from that journey...
Payment Systems
The domestic authorization flow for below-CVM-limit online contactless transactions has changed. Issuers can now ask the cardholder for a PIN or request card insertion instead of simply approving or declining. This post explains the CVM list and the new DE48 PDS22 and DE39 = 65 message flows.
ISO 8583
F37-RETRIEVAL REFERENCE NUMBER is a code generated by the bank that initiates a transaction, used to uniquely track it. It is a 12-character alphanumeric value.
ISO 8583
F32 - ACQUIRING INSTITUTION IDENTIFICATION CODE: the 11-digit acquirer bank ID. The values it can take for domestic transactions and by card brand include Visa, MasterCard, UnionPay, Discover and JCB formats.
3D Secure
Especially with the growth of the internet, credit card transactions have started shifting from physical POS terminals to virtual POS terminals. In virtual transactions, the 3D Secure structure is used instead of the card PIN entered in physical transactions. So how is a transaction's…
Merchant & POS
Partial Authorization lets an issuer approve part of a transaction instead of declining it when the balance or limit is insufficient. This post covers how it works in ISO 8583, whether it is mandatory, and why it matters for the business.
ISO 8583
F60-ADVICE REASON CODE: Used to indicate the specific purpose of an advice/reversal message. It is 60 characters long.
Online & Authorization
TLV is a data storage method used to speed up the parsing of data. For example, reading data from a card's chip at a POS and carrying it through authorization uses the TLV structure.
HSM & Security
In the world of payment systems, keys and their uses are important for transferring information from one place to another, storing information, and securing authorization and scripting steps. Key types are divided into six categories based on their purpose.
Online & Authorization
In EMV, data is stored in Tag-Length-Value (TLV) format, and it is carried between the card, the POS terminal, and the authorization system in this same format. This post lists every EMV Tag, its type, and its description.