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Merchant & POS
In EMV-based debit card transactions, PIN verification is decisive for both security and liability. What happens when a card that only supports online PIN is sent to the issuer without a PIN, and the issuer approves it? Who owns the risk?
HSM & Security
ZWK stands for Zone Working Key. It encrypts the PIN so that it can travel securely between different financial institutions, such as the acquiring bank and the issuing bank.
Credit Card
A prepaid card is a customized card, with or without a chip, not linked to a bank account and without a credit limit like credit cards, letting you spend only the amount loaded onto it.
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…
Credit Card
PVKI is the abbreviation for PIN Verification Key Index. It is located within the card's Track 1 and Track 2 data and is used in PVV calculation. It can take values from 1 to 6, usually defaulting to 1.
Payment Systems
Every payment transaction completes in seconds, yet dozens of controls run behind the scenes. This post covers the precautions for authorization and clearing, the critical role of reversals, and the financial loss scenarios most often seen in the field.
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.
Payment Systems
An official BRSA letter to banks announced an update to the PIN-free contactless payment limit. From January 15, 2026, contactless payments of up to 2,500 TL can be made without entering a PIN, up from the current 1,500 TL.
Credit Card
When we think of a credit card, we picture one printed with the Card Number, Cardholder Name, Expiration Date, and CVV2 information. But what if we told you there is a card with no numbers on it at all? It may sound strange at first, but...
Credit Card
A prepaid card is a customized chip or chipless card that is not linked to a bank account and has no credit limit like a credit card. You can only spend up to the amount loaded onto the card.
Credit Card
In the early years of credit cards, using the card physically was mandatory. With the internet and new technologies, we can now pay with only the card details, 3D Secure and contactless NFC payments, even without the card in hand.
Payment Systems
The biggest benefit of contactless payment is completing small transactions quickly. You can pay purchases under 350 TL without a PIN, while purchases above 350 TL require your card PIN.