# Definition

Authenticated payment refers to a payment method that requests a credit card payment with the authentication key after receiving the authentication result for payment from the PG. It is the most popular payment method in Korea. When a payment is requested from the checkout page, the payment window of each PG is presented to the user. Once payment is authenticated in the the payment module of the credit card company selected by the user, payment request is processed based on the authentication result.

![Basic authenticated payment flow](/files/bupx2R4DdcbupPDlNXFH)

{% hint style="info" %}
Communication for a live payment request is made directly between the merchant server and the PG server, and card information is not used in the payment request process.
{% endhint %}

#### Authenticated payment is traditionally categorized into the following two types based on the authentication method.

* ISP: authenticates pre-registered card information through a public key-based digital certificate
* MPI: authenticates card information by entering the card number, CVC, and secure click password.

Recently, most credit card companies support their own **simple payment** service that allows users to pre-register a credit card and use the **6-digit payment password** to easily make a payment.

![NHN KCP authenticated payment - Shinhan Card simple pay window](/files/IkWaNVFZ9cS0VEl07cYB)

#### You can easily integrate authenticated payment through i'mport!


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