Using out-of-band authentication SDK

Out-of-band authentication is a type of two-factor authentication that requires a secondary verification method through a separate communication channel. With out-of-band authentication, you can direct the transaction authentication requests to your secure application on an eligible cardholder's device. For example, a mobile phone.

To use the out-of-band authentication flow with your Adyen-issued cards in the European Economic Area (EEA), you need to register the cardholder's device and subsequently authenticate the transactions on this device.

We provide a client-side Authentication SDK that uses the possession factor through device binding, and either knowledge or the inherence factor, depending on the cardholder's device access configuration.

With Adyen's Authentication SDK, you can:

• Check if the cardholder's device is eligible for Strong Customer Authentication (SCA).
• Register your cardholder's mobile device to create device binding.
• Authenticate your cardholder's online card transactions with 3D Secure.

System requirements

We provide the client-side Authentication SDK in the following languages:

• Kotlin or Java for Android applications
• Swift for iOS applications

Before you start implementing the SDK, make sure that your system follows the requirements.

Installation

To install the Authentication SDK:

Register device

Before starting the device registration, make sure that the operating system on the cardholder's device supports SCA.

The following are the steps you need to do to register the cardholder's device.

1. Check SCA eligibility.
2. Initiate the device registration from your server.
3. Authenticate the cardholder.
4. Register the device.
5. Finalize the registration from your server.

Step 1. Check SCA eligibility

Step 2. Initiate device registration

Registering the device is a one-off procedure. You can only register one device per payment instrument. If you register a new device for a payment instrument that previously had a registered device, this will remove the binding with the old device.

To start the device registration:

1. From your server, make a POST /registeredDevices request. To make this request, your API credential needs the following role:

   • Bank SCA Webservice Role

   Reach out to you Adyen contact to set it up for you.

   In the request, specify the following:

   Parameter	Description
   paymentInstrumentId	The unique identifier of the payment instrument you want to register the device for.
   strongCustomerAuthentication.sdkOutput	Base64-encoded blob of data created in the previous step.

   The response returns:

   • sdkInput: pass it to the SDK when registering the device.
   • id: device ID needed when finalizing the registration.

   We suggest that you create and store a mapping between the registered device id and the human-readable account holder name. For example, RD00000000000000000000001 is "Cardholder's iPhone". You can use this pair later to show the details, for example, when unbinding the device.

Step 3. Authenticate cardholder

In your client app, perform cardholder authentication. PSD2 requires you to perform two-factor authentication (2FA) as an extra security step during the login process.

Step 4. Register the device

After you successfully authenticate your cardholder:

1. Trigger the SDK to start the device registration and pass sdkInput from step 2.

   Kotlin Swift

   Kotlin Swift

   After the successful registration, the SDK generates a Base64-encoded sdkOutput data blob.

   Trigger the SDK to start the device registration and pass sdkInput.

   The SDK uses the Apple DeviceCheck framework to generate a Base64-encoded sdkOutput data blob. To do this, the SDK authenticates the user using Touch ID, Face ID, or the device passcode. To enable Face ID support, add NSFaceIDUsageDescription to Info.plist.

2. Pass sdkOutput to your server.

Step 5. Finalize registration

To finalize the device registration:

1. From your server, make a PATCH /registeredDevices/{id} request, specifying the device id in the path and the following parameters in the request body:

   Parameter	Description
   paymentInstrumentId	The unique identifier of the payment instrument you want to register the device for.
   strongCustomerAuthentication.sdkOutput	Base64-encoded blob of data created in the previous step.

   The response contains success true.

The registration is now complete. The cardholder can start authenticating future transactions using your app.

Authenticate cardholder

Each time your cardholder makes a transaction that requires 3D Secure, you need to authenticate them. The authentication time frame is valid for 10 minutes.

The following are the steps you need to do to authenticate the cardholder.

1. Set up a webhook endpoint.
2. Accept the authentication webhook.
3. Authenticate the cardholder.
4. Finalize the cardholder authentication from your server.

Step 1. Set up a webhook endpoint

Your integration must be able to receive and process webhooks for authentication requests.

1. Create an endpoint on your server that:

   • Can receive a JSON object.
   • Has an open TCP port for HTTPS traffic on port 443, 8443, or 8843.
   • Can handle basic authentication.

2. Send the endpoint URL to your Adyen contact.

To learn more about setting up webhooks, see Set up webhooks.

Step 2. Accept authentication webhooks

When the cardholder makes a transaction that requires authentication, we send a webhook to your server. Your server must respond to the webhook within 10 seconds. Otherwise, the authentication process will fail. The webhook contains the following parameters:

In the request header:

Parameter	Description
sdkInput	SCA realm="Challenge" authparm1="{sdkInput}" where sdkInput is a Base64-encoded blob of data to be passed to the SDK in the next step.

In the request body:

Parameter	Description
id	A unique reference of the 3D Secure challenge.
paymentInstrumentId	The unique identifier of the payment instrument. Use this field to direct the authentication request to the correct cardholder.
purchase	An object containing the details of the purchase, such as date, merchant name, and amount.

To ensure that your server has accepted the webhook, we require you to acknowledge every webhook with an HTTP 200 response containing the following:

If we don't receive the response message within 10 seconds or receive status set to refused, the authentication process will stop.

For more information about webhook setup and best practices, see Set up webhooks.

Step 3. Authenticate cardholder

Your application must display the data from the previous step to the cardholder during the authentication. We recommend that you implement a push notification and use the data from the webhook to inform the cardholder about the details of the transaction they are authenticating for.

After being prompted on the merchant interface, the cardholder proceeds to the application.

Authenticate your cardholder using the SDK. To do so:

1. Trigger the SDK to start cardholder authentication and pass the sdkInput value from the previous step.

   Kotlin Swift

   Kotlin Swift

   If successful, the result is a Base64-encoded sdkOutput data blob.

   In case of any error that occurs at this stage, return to the check SCA eligibility step and perform the registration steps again.

2. Pass sdkOutput to your server.

Step 4. Finalize authentication

You must finalize the authentication within 10 minutes of receiving the request. To finalize the authentication:

1. From your server, make a PATCH /challenges request, specifying the following parameters:

   In the path:

   Parameter	Description
   id	The challengeReference value from the webhook in Step 2.

   In the request header:

   Parameter	Description
   www-authenticate	Set SCA realm to Challenge. Set authparm1 with the Base64-encoded value of sdkOutput from cardholder authentication.

   In the request body:

   Parameter	Description
   completed	Set to true.

   If successful, the response contains the id of the challenge and challengeCompleted: true.

   {
       "id": "778a7bd0-0f08-4d0b-b6ec-76c3a47f775c",
       "challengeCompleted": true
   }

Get updates

We will notify you of the status and outcome of the authentication once the cardholder has completed 3D Secure authentication. Regardless of whether the authentication process was successfully completed, failed, or expired, we send the balancePlatform.authentication.created webhook.

To keep track of webhooks, make sure that your server can receive and accept webhooks.

The balancePlatform.authentication.created webhook contains the following information.