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Diagram showing the components of the External Authenticate command

EMV

What is the External Authenticate Command?

The EXTERNAL AUTHENTICATE command asks the application inside the ICC whether it can verify the cryptogram, and the ICC returns the processing status. Below are the components of the External Authenticate command and what issuer authentication means.

Illustration representing Strong Customer Authentication (SCA) under PSD2

Payment Systems

What is Strong Customer Authentication (SCA)?

Strong Customer Authentication (SCA) is a security requirement introduced under the EU's Payment Services Directive 2 (PSD2) to increase security and reduce fraud in online payment transactions. SCA requires two of three independent authentication factors.

Diagram showing the EMV chip card static data authentication (SDA) process

EMV

What is a Data Authentication Code (DAC)?

DAC is the abbreviation for Data Authentication Code. It is a piece of data assigned by the issuer and held by the terminal during the Signed Static Application Data verification process.

Diagram showing the Terminal Authentication Key (TAK) concept

HSM & Security

What is TAK (Terminal Authentication Key)?

TAK stands for Terminal Authentication Key. It is the data encryption key used to generate and verify a Message Authentication Code (MAC) for data communication between a terminal and the acquirer within a local network.

Table of CAVV result codes and what they mean for merchants

Merchant & POS

What is CAVV? What is AAV?

CAVV and AAV are verification codes used in 3D Secure transactions to ensure transaction integrity and security. CAVV is used by Visa, while AAV is used by Mastercard.

Diagram illustrating the EMV Tag-Length-Value (TLV) data structure used in card transactions

Online & Authorization

What are EMV Tags?

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.

Diagram illustrating how a transaction's 3D Secure authentication level is determined

3D Secure

How is a transaction's 3D Secure level determined?

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…

Diagram showing Electronic Commerce Indicator values used in 3D Secure transactions

Online & Authorization

What is the Electronic Commerce Indicator (ECI)?

Electronic Commerce Indicator (ECI) is a 2-digit value generated by payment schemes (Visa, MasterCard, etc.) in 3D Secure transactions to determine the transaction's security level (Full 3D Secure, Half 3D Secure, Non 3D Secure), and it varies by payment scheme.

Diagram illustrating SDA, DDA, and CDA offline data authentication methods

Credit Card

What are SDA, DDA, and CDA?

SDA (Static Data Authentication), DDA (Dynamic Data Authentication), and CDA (Combined Dynamic Data Authentication) are offline data authentication methods used in chip cards. Learn how each one validates the card and the transaction.

Architecture diagram of the Visa EAS Server within the Visa Secure 3-D Secure authentication flow

EMV

What Is the Visa EAS Server?

The Visa EAS Server (Extended Access Service) is a server used in Visa’s authentication infrastructure. It was developed to run the cardholder authentication process securely between banks and the Visa network, particularly within Visa Secure (3-D Secure 2.x).

Diagram explaining 3D Secure, Half 3D, and Non 3D e-commerce transaction levels

Merchant & POS

What is an E-commerce Transaction?

E-Commerce can briefly be described as the sale and purchase of products over the internet, a term used since 1969. Virtual POS operates behind e-commerce transactions, which take place at different levels: Non 3D, Half 3D, and Full 3D Secure.