[Openid-specs-ab] Comments on Registration (-14) Release Candidate D

[Brian Campbell]

Some comments/questions on
http://openid.net/specs/openid-connect-registration-1_0-14.html follow:

http://openid.net/specs/openid-connect-registration-1_0-14.html#ClientRegistration
2.1.  Client Registration and Client Update Request

The definition of access_token and the text near the bottom about
registration_access_token seem to suggest that the (registration) access
token need only be sent on client_update requests. But surly it's also
needed for rotate_secret?

Changing from requiring client id and secret on client_update (and I assume
rotate_secret) to needed the registration access token suggests that (short
of some additional work) clients provisioned by some other means than this
registration endpoint cannot update themselves or rotate their secret via
the registration endpoint. I guess that could be a feature or a bug (or
just meh) depending on how you look at it. But it just occurred to me and
the change is relatively recent so I thought I'd mention it.

Honestly, it feels pretty awkward that the nature of the access token and
if it's required or not differs based on the value of the operation
parameter. It can work but means that the code that's doing the authn/z
will need to examine the operation parameter in the request body in order
to know what to do and the content of the token and how it's processed
might be very different based on the operation.  Anyway, I'm not
necessarily objecting to it but still feel compelled to mention that it
leaves kind of a bad taste.

jwk_url and x509_url say they are used for "signing Token Endpoint
Requests" but there's nothing specified anywhere about signing Token
Endpoint Requests, is there? Is it intended to mean signing the jwt when
authenticating to the token endpoint using the private_key_jwt method?

All the jwk and x509 basically say that if both jwk and x509 are registered
then. "the keys contained in both formats SHOULD be the same" but Messages
4.2 http://openid.net/specs/openid-connect-messages-1_0-15.html#sigenc.keyhas
a MUST. Shouldn't these be consistent?

Issues 703 and 704 likely will impact the key parameters too.

A number of places say "The valid values are listed in Section 3.1 of
JWA<http://openid.net/specs/openid-connect-registration-1_0-14.html#JWA>[JWA]"
with respect to signing. But is "none" an acceptable/reasonalbe
value for any or all of these?


http://openid.net/specs/openid-connect-registration-1_0-14.html#ClientRegisterResponse
2.2.1.  Client Register Operation Response

says that "[client_secret] is not required for clients selecting a
token_endpoint_auth_method of private_key_jwt" but what if they've selected
HS256 (or other HSxxx) for request_object_signing_alg or any of the
*signed* or *singing* parameters?

This section and 2.2.3 have "Additionally, the server MUST include all
registered metadata about a client as described in Section
2.1<http://openid.net/specs/openid-connect-registration-1_0-14.html#ClientRegistration>,
including any fields that the server has provisioned on the client's
behalf." What is the expected behavior for default values from 2.1 (that
very well might not be stored anywhere).

http://openid.net/specs/openid-connect-registration-1_0-14.html#ErrorResponse
2.3.  Client Registration Error Response

I don't think invalid_client_id or invalid_client_secret are valid anymore?


http://openid.net/specs/openid-connect-registration-1_0-14.html#Security
5.  Security Considerations
"Requests to the Registration Endpoint for client_update MUST have some
rate limiting on failures to prevent the Client secret from being disclosed
though repeated access attempts." Which is true, I suppose, but no longer
applies to the client secret but rather to the registration access token.
Also doesn't it apply to rotate_secret as well?


http://openid.net/specs/openid-connect-registration-1_0-14.html#Acknowledgements
Appendix A.  Acknowledgements

Is empty. What does it take to get on there? ;) I'm sure I'm not the only
one either...


Thanks,
Brian


P.S. I'll try and look at the other RC docs in the next few days but it's
very time consuming and not the only thing on my (or anyone's I'm sure)
plate. I just happened to be trying to update some of my (limited)
registration code today so it was right in front of me.
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