Which connection method should I choose?

It depends on what the needs are. Should only authentication be offered or is signing also being used.

Auðkenni offers three types of communication interfaces. OpenID Connect, REST API interface, and CIBA (Client Initiated Backchannel Authentication).

If digital signing is also used

If authentication and signing capabilities are to be used, CIBA is the way to go.

If only authentication

If only authentication options are to be used, there are more ways available:

CIBA

A secure method that requires security from the client tool being used. It also requires equipment certificates to use this method.
Here, the service provider creates a login page that faces the user. At the same time, the service provider has full control over its appearance and functionality.

Step-by-step instructions:

CIBA	SIM	APP

CIBA	SIM	APP
Authentication	SIM Authentication using CIBA	APP Authentication using CIBA - Device Link APP Authentication using CIBA
Signature	SIM Signing using CIBA (PKCS7)	APP Signing using CIBA (Any Cert) - Device Link APP Signing using CIBA (Any Cert)
Signature	SIM Signing using CIBA (PKCS1)	APP Signing using CIBA (Selected Cert/device) - Device Link APP Signing using CIBA (Selected Cert/device)

OpenId Connect (OIDC)

A convenient and straightforward standardized method.
Here, the login page provided by Auðkenni is used. The service provider, therefore, doesn't need to create it and, as a result, doesn't have control over its appearance and functionality.

OIDC Integration Guide

REST API

A simple and convenient API interface. This method does not require as much security from the client tool as the CIBA method.
Here, the service provider creates a login page that faces the user. At the same time, the service provider has full control over its appearance and functionality.
Most new service providers are choosing this method.