I've seen a lot of questions regarding OAuth and using it to secure APIs using an external trusted provider.
However, in our organization, we have an existing ASP.NET MVC web application which contains a custom membership provider for authenticating users to use the web application. We are now developing an API (which will be accessed externally) which allows users of the API develop their own clients.
I am looking into different ways to secure the API without passing user credentials. The API will force HTTPS, but the security team does not want user credentials stored on the client systems. I have considered, a token based approach -- but most posts I have read here seem to suggest OAuth. Would the preferable route be some sort of OAuth implementation? And if so, how do I authenticate internal users who are not registered with a trusted provider?
Thanks!