Re: [OAUTH-WG] Second AD Review: draft-ietf-oauth-mtls

Hi Brian!

My response is inline ...

From: Brian Campbell [mailto:bcampbell@pingidentity.com]
Sent: Monday, June 24, 2019 1:17 PM
To: Roman Danyliw <rdd@cert.org>
Cc: oauth <oauth@ietf.org>
Subject: Re: [OAUTH-WG] Second AD Review: draft-ietf-oauth-mtls

Thanks for the additional review, Roman. I feel lucky, it's not often one gets *two* AD reviews :)  Please see below for replies inline with a few followup questions.

[Roman] *chuckle*

On Sat, Jun 22, 2019 at 12:29 PM Roman Danyliw <rdd@cert.org<mailto:rdd@cert.org>> wrote:
Hi!

I conducted as second AD review of draft-ietf-oauth-mtls per the AD hand-off.  I have the following additional feedback:

** Per ekr's earlier review at https://mozphab-ietf.devsvcdev.mozaws.net/D3657, paraphrasing:
-- Section 2.1.2, How is these metadata parameters being obtained?

The authorization server can obtain client metadata via the Dynamic Client Registration Protocol [RFC7591], which is referenced in the top of that section. Also the metadata defined by RFC7591, and registered extensions to it, implies a general data model for clients that is used by most authorization server implementations even when the Dynamic Client Registration Protocol isn't in play. Such implementations typically have some sort of  user interface available for managing client configuration.

Dose that answer your question? Do you believe more should be said in the document to better explain or clarify that?

[Roman]  It does clear it up.  Thanks.  I think it’s worth a short statement about how the AS would get the fields.

-- Section 3.2, Figure 3.  In this example, what new information is the auth server providing to the relying party here?

The new info here (and in Section 3.1 too) is the hash of the client certificate to which the access token is bound, which is in the "cnf" confirmation method at the bottom as the "x5t#S256" member.

[Roman]  Makes sense.  To make the example clearer, I’d call out this out in the prose introducing the example.

** Section 2.0.  What is the expected behavior if the presented certificate doesn't match expected client_id?  How is this signaled?

With a normal OAuth 2.0 error response using the "invalid_client" error code per https://tools.ietf.org/html/rfc6749#section-5.2

Do you think that needs to be stated more explicitly in this document?

[Roman] Yes, I’d explicit state it with that citation, especially since Section 3 discusses of how errors are returned.

** Section 2.2.  Per the sentence "As pre-requisite, the client registers its X.509 certificate ... or a trusted source for its X.509 certificates ... with the authorization server.
-- Editorial: s/As pre-requisite/As a prerequisite/

done

-- What's a "trusted source" in this case?  Is that just a jwks_uri?  If so, maybe s/a trusted source/a reference to a trust source/.  If not, can you please elaborate.

Yes, it's just a jwks_uri. I'll change that.

A few editorial nits:
** Section 2.2.2.  Typo.  s/sec 4.7/Section 4.7/

fixed

** Section 3.1  Cite DER encoding as:
    [X690]     ITU-T, "Information Technology -- ASN.1 encoding rules:
              Specification of Basic Encoding Rules (BER), Canonical
              Encoding Rules (CER) and Distinguished Encoding Rules
              (DER)", ITU-T Recommendation X.690, 2015.

will do

** Section 5.  Typo. s/metatdata/metadata/

yup

** Section 6.  Typo.  s/The the/The/

got it

** Section 7.2. Typo.  s/the the/the/

done

** Appendix. Cite the figures numbers (#5 - 7) in the text describing the contents of the section.

will do

The shepherd write-up is in good shape.  Thank you.

Regards,
Roman

[Roman] Thanks for all of the above.

Roman

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