Although OAuth is not for authentication (the "auth" is for authorization), it usually presupposes that an authentication event has taken place. In the case of the Axway API Gateway, you can use the internal use store for this authentication, or you can use a third-party repository like LDAP. If you want to switch to LDAP, you can simply choose a different authentication repository under "Validate credentials against this repository" in the OAuth 2.0 policies in Policy Studio as shown below:

If you want to add a new authentication repository, you can find these under "Authentication Repositories" in Policy Studio, as shown below:


Note that other options include CA SiteMinder, Oracle Access Manager, IBM Tivoli Access Manager, and others.