Federated vs. Delegated, OAuth vs OpenID Connect vs SAML

Question

I am trying to understand differences between Federated Authentication and Delegated Authentication, But I am getting more and more confused.

1. Do we use SAML protocol ALWAYS for Federated Authentication? or What?

2. Is it possible to use OpenID Connect (or OAuth) for both authentication methods?

3. Do we need to have Trusted connection between two domains to be able to have Delegated or Federated authentication?

4. Do we always use SAML for Partners and OpenID Connect (or OAuth) for Customers?

5. I will be grateful if somebody explains different steps for these two authentication methods between two domains (Partners and Enterprise).

Answer 1

A difference between the two methods are:

A delegated solution means that one site is simply outsourcing its authentication needs to another pre-selected site. If your site uses Facebook Connect, you are delegating your authentication facilities to Facebook. Visitors to your site cannot use any other accounts, only accounts from the vendors you have pre-selected.

A federated solution means that visitors to your site can use any account they have, as long as it is compatible. It makes no difference to the site which account is being used, as long as it can interoperate. At its core, OpenID is a federated solution because its most important feature is the ability to use any OpenID account with any OpenID-enabled service.

Source

Now to your questions:

1. Not only SAML but OpenId Connect, OAtuh2 or even others protocols can be used as well.
2. Yes. Just note that delegated solution is less secure.