For the purpose of carrying out a payment initiation with the XS2A APIs, it is necessary to establish a consent between the TPP, the PSU and the ASPSP.

Redirect OAuth2

In this approach, the PISP has to proceed with an OAuth2 authorization. The consent is established and validated thanks to a redirection of the PSU towards the ASPSP Authentication platform.
See How to Perform a Strong Customer Authentication for details.

Payment Initiation
Initiate Payment Resource
POST /berlingroup/v1/{payment-service}/{payment-product}

Creates a payment resource at the ASPSP for a given payment service and product. Specificities for this API and available services and products are listed in the dedicated HowTo.

Create an authorisation resource on a given payment
POST /berlingroup/v1/{payment-service}/{payment-product}/{paymentId}/authorisations

Create an authorisation sub-resource of the payment resource and start the authorisation process.

The usage of this access method is only necessary if the TPP has asked to start the authorisation process separately from the payment initiation (using the “TPP-Explicit-Authorisation-Preferred” Header).

Authorization request
GET /berlingroup/authorization/authorize/{authorisation-id}

Requests an authorisation from a PSU following the OAuth2 protocol. Details of the authentication workflow and user interfaces are described in the dedicated HowTo section.
Our specificities regarding the OAuth2 protocol are listed below.

response_type : code
code_challenge_method : S256

After successful authorisation, the user will be redirected to the redirect URI provided in the request with the following parameters :

Specific BerlinGroup Implementation on Payment Initiation Service

For specific BerlinGroup Implementation on the Payment Initiation Service, please refer to specific implementation How To.