Re: [OAUTH-WG] [UNVERIFIED SENDER] Re: MTLS and in-browser clients using the token endpoint

[Brian Campbell <[e-mail]>]

Yeah, probably.

On Sat, Feb 2, 2019 at 12:39 AM Neil Madden <[e-mail]>
wrote:

> If we go down the 307 route, shouldn’t it rather be a 308 (permanent)
> redirect? It seems unnecessary for the client to keep trying the original
> endpoint or have to remember cache-control/expires timeouts.
>
> — Neil
>
> On 2 Feb 2019, at 00:03, Richard Backman, Annabelle <
> richanna=[e-mail]> wrote:
>
> Confusion from the AS’s perspective:
>
>    1. If I only support mTLS, do I need to include both
>    token_endpoint_uri and mtls_endpoints? Should I omit token_endpoint_uri? Or
>    set it to the empty string?
>    2. What if I only support mTLS for the token endpoint, but not
>    revocation or user info?
>    3. How do I specify authentication methods for the mTLS token
>    endpoint? Does token_endpoint_auth_methods apply to both the mTLS and
>    non-mTLS endpoints?
>    4. I’m using the OAuth 2.0 Device Flow. Do I include a mTLS-enabled
>    device_authorization_endpoint under mtls_endpoints?
>
>
>
> Confusion from the client’s perspective:
>
>    1. As far as I know, I’m a public client, and don’t know anything
>    about mTLS, but the IT admins installed client certs in their users’
>    browsers and the AS expects to use that to authenticate me.
>    2. My AS metadata parser crashed because the mTLS-only AS omitted
>    token_endpoint_uri.
>    3. My AS metadata parser crashed because it didn’t expect to encounter
>    a JSON object as a parameter value.
>    4. The mTLS-only AS didn’t provide a value for mtls_endpoints, what do
>    I do?
>    5. I don’t know what that “m” means, but they told me to use HTTPS, so
>    I should use the one with “tls” in its name, right?
>
>
>
> Yes, you can write normative text that answers most of these. But you’ll
> have to clearly cover a lot of similar-but-slightly-different scenarios and
> be very explicit. And implementers will still get it wrong. The metadata
> change introduces opportunities for confusion and failure that do not exist
> now, and forces them on everyone who supports mTLS. In contrast, the 307
> redirect is only required when an AS wants to support both, and is
> unambiguous in its behavior and meaning.
>
>
>
> --
>
> Annabelle Richard Backman
>
> AWS Identity
>
>
>
>
>
> *From: *Brian Campbell <bcampbell=[e-mail]>
> *Date: *Friday, February 1, 2019 at 3:17 PM
> *To: *"Richard Backman, Annabelle" <[e-mail]>
> *Cc: *George Fletcher <[e-mail]>, oauth <[e-mail]>
> *Subject: *[UNVERIFIED SENDER] Re: [OAUTH-WG] MTLS and in-browser clients
> using the token endpoint
>
>
>
> It doesn't seem like that confusing or large of a change to me - if the
> client is doing MTLS and the given endpoint is present in `mtls_endpoints`,
> then it uses that one.  Otherwise it uses the regular endpoint. It gives an
> AS a lot of flexibility in deployment options. I personally think getting a
> 307 approach deployed and working would be more complicated and error
> prone.
>
>
>
> It is a minority use case at the moment but there are forces in play, like
> the push for increased security in general and to have javascript clients
> use the code flow, that suggest it won't be terribly unusual to see an AS
> that wants to support MTLS clients and javascript/spa clients at the same
> time.
>
>
>
> I've personally wavered back and forth in this thread on whether or not to
> add the new metadata (or something like it). With my reasoning each way
> kinda explained somewhere back in the 40 or so messages that make up this
> thread.  But it seems like the rough consensus of the group here is in
> favor of it.
>
>
>
>
>
>
>
>
>
> On Fri, Feb 1, 2019 at 3:18 PM Richard Backman, Annabelle <richanna=
> [e-mail]> wrote:
>
> This strikes me as a very prominent and confusing change to support what
> seems to be a minority use case. I’m getting a headache just thinking about
> the text needed to clarify when the AS should provide `mtls_endpoints` and
> when the client should use that versus using `token_endpoint.` Why is the
> 307 status code insufficient to cover the case where a single AS supports
> both mTLS and non-mTLS?
>
>
>
> --
>
> Annabelle Richard Backman
>
> AWS Identity
>
>
>
>
>
> *From: *OAuth <[e-mail]> on behalf of Brian Campbell
> <bcampbell=[e-mail]>
> *Date: *Friday, February 1, 2019 at 1:31 PM
> *To: *George Fletcher <gffletch=[e-mail]
> <40aol.com@dmarc...ietf.org>>
> *Cc: *oauth <[e-mail]>
> *Subject: *Re: [OAUTH-WG] MTLS and in-browser clients using the token
> endpoint
>
>
>
> Yes, that would work.
>
>
>
> On Fri, Feb 1, 2019 at 2:28 PM George Fletcher <gffletch=
> [e-mail]..org <[e-mail]>> wrote:
>
> What if the AS wants to ONLY support MTLS connections. Does it not specify
> the optional "mtls_endpoints" and just use the normal metadata values?
>
> On 1/15/19 8:48 AM, Brian Campbell wrote:
>
> It would definitely be optional, apologies if that wasn't made clear..
> It'd be something to the effect of optional for the AS to include and
> clients doing MTLS would use it when present in AS metadata.
>
>
>
> On Tue, Jan 15, 2019 at 2:04 AM Dave Tonge <[e-mail]>
> wrote:
>
> I'm in favour of the `mtls_endpoints` metadata parameter - although it
> should be optional.
>
>
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