Office 365 authentication via REST without registering an application

Question

Is there any way of authenticating a user via the Office 365 REST API, without registering an application first?

For example, the documentation of Microsoft Graph has numerous authentication scenarios, including how an application can

• Get access on behalf of a user

but there is no such scenario for a user calling the REST API with some credentials (e.g., username and password) and gets authentication tokens as a response, so that they can subsequently use the rich functionality provided.

The Azure Active Directory Authentication Libraries (ADAL) provide user-level authentication functionality, but they do not expose the REST API.

Answer 1

There is no way to call the Microsoft Graph without registering an app first. All calls to the graph are authenticated using a OAuth2 flow (of which there are several) and all require an app to be registered.

Answer 2

For your question, I think we can use background daemons or services to get authorize the user.We can use the following steps:

1. Get access without a user. We can refer to this document to learning more information.

2.Authorize the user When we get the user's profile by using the access token in the step one, then we can authorize him by checking him is exist in our system.