[OpenID] Does Application Type correspond to Client Type?

[Takahiko Kawasaki]

If "Native Clients" in "OpenID Connect Dynamic Client Registration
1.0, 2. Client Metadata" means "native application" in "RFC 6749
(OAuth 2.0), 2.1 Client Types" (yes it apparently does), "Native
Clients" are always 'public' clients.

If "Web Clients" in "OpenID Connect Dynamic Client Registration 1.0,
2. Client Metadata" means "web application" in "RFC 6749 (OAuth 2.0),
2.1 Client Types" but does not include "user-agent-based application",
"Web Clients" are always 'confidential' clients.

Using the above interpretation, application_type=native and
application_type=web correspond to 'public' and 'confidential',
respectively.

However, the requirement of application_type:

    Web Clients using the OAuth Implicit Grant Type MUST only
    register URLs using the https scheme as redirect_uris; they
    MUST NOT use localhost as the hostname. Native Clients MUST
    only register redirect_uris using custom URI schemes or URLs
    using the http: scheme with localhost as the hostname.

is irrelevant to whether or not clients are "capable of maintaining
the confidentiality of their credentials" (from RFC 6749). In other
words, redirect URIs are irrelevant to how to authentication clients.
Therefore, it sounds to me that Application Type and Client Type are
different concepts.

It is weird that all "OAuth 2.0 clients" must comply with either of
the 'redirect_uris' requirements (one is for Web Clients and the
other is for Native Clients), so probably it is inappropriate that
'web' is used as the default value when application_type is omitted.
IMHO, neither of 'native' nor 'web' should be assumed when
application_type is omitted. But, I may be missing something. Is
there any reason to impose the 'redirect_uris' requirements on all
"OpenID Connect clients"?

Anyway, my conclusion is that Application Type and Client Type are
different. And I hope that client_type (public or confidential) is
added to the list of Client Metadata and that neither of 'native'
nor 'web' is used as the default value when application_type is not
contained in client registration requests.

--
Best Regards,
Takahiko Kawasaki


2014-05-10 10:29 GMT+09:00 Takahiko Kawasaki <daru.tk at gmail.com>:
> Hello,
>
> I'm wondering whether this is the right place to ask my question.
> If not, please tell me so.
>
> I posted a question to StackOverflow, but no answer yet.
>
>   http://stackoverflow.com/q/23557801/1174054
>
> My question is "Does Application Type (OpenID Connect) correspond to
> Client Type (OAuth 2.0)?" Could anyone give me an answer please?
> Below is the detail of the question.
>
> "OpenID Connect Dynamic Client Registration 1.0, 2. Client Metadata"
> has an entry named application_type, whose defined values are
> 'native' and 'web'.
>
>   --- Excerpt from OpenID Connect Dynamic Client Registration ------
>   application_type
>     OPTIONAL. Kind of the application. The default, if omitted, is
>     web. The defined values are native or web. Web Clients using the
>     OAuth Implicit Grant Type MUST only register URLs using the
>     https scheme as redirect_uris; they MUST NOT use localhost as
>     the hostname. Native Clients MUST only register redirect_uris
>     using custom URI schemes or URLs using the http: scheme with
>     localhost as the hostname. Authorization Servers MAY place
>     additional constraints on Native Clients. Authorization Servers
>     MAY reject Redirection URI values using the http scheme, other
>     than the localhost case for Native Clients. The Authorization
>     Server MUST verify that all the registered redirect_uris conform
>     to these constraints. This prevents sharing a Client ID across
>     different types of Clients.
>   ------------------------------------------------------------------
>
> Do these defined values correspond to 'public' and 'confidential'
> described in "RFC 6749 (OAuth 2.0), 2.1. Client Types"?
>
>   --- Excerpt from RFC 6749 (OAuth 2.0) ----------------------------
>   OAuth defines two client types, based on their ability to
>   authenticate securely with the authorization server (i.e., ability
>   to maintain the confidentiality of their client credentials):
>
>     confidential
>       Clients capable of maintaining the confidentiality of their
>       credentials (e.g., client implemented on a secure server with
>       restricted access to the client credentials), or capable of
>       secure client authentication using other means.
>
>     public
>       Clients incapable of maintaining the confidentiality of their
>       credentials (e.g., clients executing on the device used by the
>       resource owner, such as an installed native application or a
>       web browser-based application), and incapable of secure client
>       authentication via any other means.
>   ------------------------------------------------------------------
>
> If not, why doesn't the specification (OpenID Connect Dynamic Client
> Registration 1.0) have an entry to specify a client type? Is there
> any way to specify a client type (public or confidential) at the
> client registration endpoint?
>
>
> --
> Best Regards,
> Takahiko Kawasaki