[OAUTH-WG] Issue: Split the authorization endpoint into two endpoints

[Eran Hammer-Lahav <[e-mail]>]

OAuth 2.0 defines a single authorization endpoint with a 'type' parameter
for the various flows and flow steps. There are two types of calls made to
the authorization endpoint:

- Requests for Access - requests in which an end user interacts with the
authorization server, granting client access.

- Requests for Token - requests in which the client uses a verification code
or other credentials to obtain an access token. These requests require
SSL/TLS because they always result in the transmission of plaintext
credentials in the response and sometimes in the request.

A proposal has been made to define two separate endpoints due to the
different nature of these endpoints:

On 4/6/10 4:06 PM, "Marius Scurtescu" <[e-mail]> wrote:

> Constraints for endpoints:
> access token URL: HTTPS and POST only, no user
> user authentication URL: HTTP or HTTPS, GET or POST, authenticated user
> 
> In many cases the above constraints can be enforced with configuration
> that sits in front of the controllers implementing these endpoints.
> For example, Apache config can enforce SSL and POST. Same can be done
> in a Java filter. Also a Java filter can enforce that only
> authenticated users hit the endpoint, it can redirect to a login page
> if needed.
> 
> By keeping two different endpoints all of the above is much simpler.
> Nothing prevents an authz server to collapse these two into one
> endpoint.

While requests for access do not require HTTPS, they should because they
involve authenticating the end user. As for enforcing HTTP methods (GET,
POST), this is simple to do both at the server configuration level or
application level.

On the other hand, having a single endpoint makes the specification simpler,
and more importantly, makes discovery trivial as a 401 response needs to
include a single endpoint for obtaining a token regardless of the flow (some
flows use one, others two steps).

A richer discovery later can use LRDD on the single authorization endpoint
to obtain an XRD describing the flows and UI options provided by the server.
But this is outside our scope.

Proposal: No change. Keep the single authorization endpoint and require
HTTPS for all requests.

EHL