Re: [OAUTH-WG] I-D Action: draft-ietf-oauth-token-exchange-07.txt

Hi All,

The last email from Brian addresses the multiple audiences/resources issue
with an error code, and we did not see any objection to this approach so
far.

*Authors,*

Are there any other open issues with this draft?
Do you believe it is ready for WGLC?

Thanks,
 Rifaat & Hannes

On Fri, Mar 31, 2017 at 11:03 AM, Brian Campbell <bcampbell@pingidentity.com
> wrote:

> As mentioned during the Chicago meeting the "invalid_target" error code
> that was added in -07 was intended to give the AS a standard way to reject
> request with multiple audiences/resources that it doesn't understand or is
> unwilling or unable to process based on policy or whatever criteria . It
> was intended as a compromise, of sorts, to allow for the multiple
> resources/audiences in the request but provide an easy out for the AS of
> saying it can't be supported based on whatever implementation or security
> or policy it has.
>
> On Tue, Mar 28, 2017 at 1:32 AM, Nat Sakimura <sakimura@gmail.com> wrote:
>
>> There are cases where tokens are supposed to be consumed at multiple
>> places and the `aud` needed to capture them. That's why `aud` is a
>> multi-valued field.
>>
>> On Mon, Mar 27, 2017 at 11:35 AM Torsten Lodderstedt <
>> torsten@lodderstedt.net> wrote:
>>
>>> May I ask you to explain this reason?
>>>
>>> Am 27.03.2017 um 08:48 schrieb Mike Jones <Michael.Jones@microsoft.com>:
>>>
>>> For the same reason that the “aud” claim is multi-valued in JWTs, the
>>> audience needs to stay multi-valued in Token Exchange.  Ditto for resources.
>>>
>>>
>>>
>>>                                                        Thanks,
>>>
>>>                                                        -- Mike
>>>
>>>
>>>
>>> *From:* OAuth [mailto:oauth-bounces@ietf.org <oauth-bounces@ietf.org>] *On
>>> Behalf Of *Brian Campbell
>>> *Sent:* Monday, March 27, 2017 8:45 AM
>>> *To:* Torsten Lodderstedt <torsten@lodderstedt.net>
>>> *Cc:* oauth <oauth@ietf.org>
>>> *Subject:* Re: [OAUTH-WG] I-D Action: draft-ietf-oauth-token-exchang
>>> e-07.txt
>>>
>>>
>>>
>>> Thanks for the review and question, Torsten.
>>>
>>> The desire to support multiple audience/resource values in the request
>>> came up during a review and discussion among the authors of the document
>>> when preparing the -03 draft. As I recall, it was said that both Salesforce
>>> and Microsoft had use-cases for it. I incorporated support for it into the
>>> draft acting in the role of editor.
>>>
>>> From an individual perspective, I tend to agree with you that allowing
>>> for multiple audiences/resources adds a lot of complexity that's like not
>>> needed in many (or most) cases. And I would personally be open to making
>>> audience and resource mutual exclusive and single valued. A question for
>>> the WG I suppose.
>>>
>>> The "invalid_target" error code that was added in -07 was intended to
>>> give the AS a standard way to deal with the complexity and reject request
>>> with multiple audiences/resources that it doesn't understand or is
>>> unwilling or unable to process. It was intended as a compromise, of sorts,
>>> to allow for the multiples but provide an easy out of saying it can't be
>>> supported based on whatever implementation or policy of the AS.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Sun, Mar 26, 2017 at 9:00 AM, Torsten Lodderstedt <
>>> torsten@lodderstedt.net> wrote:
>>>
>>> Hi Brian,
>>>
>>>
>>>
>>> thanks for the clarification around resource, audience and scope.
>>>
>>>
>>>
>>> Here are my comments on the draft:
>>>
>>>
>>>
>>> In section 2.1 it states: „Multiple "resource" parameters may be used to
>>> indicate
>>>
>>>       that the issued token is intended to be used at the multiple
>>>
>>>       resources listed.“
>>>
>>>
>>>
>>> Can you please explain the rational in more detail? I don’t understand
>>> why there is a need to ask for access tokens, which are good for multiple
>>> resources at once. This is a request type more or less exclusively used in
>>> server to server scenarios, right? So the only reason I can think of is
>>> call reduction.
>>>
>>>
>>>
>>> On the other side, this feature increases the AS's complexity, e.g. its
>>> policy may prohibit to issue tokens for multiple resources in general or
>>> the particular set the client is asking for. How shall the AS handles such
>>> cases?
>>>
>>>
>>>
>>> And it is getting even more complicated given there could also be
>>> multiple audience values and the client could mix them:
>>>
>>>
>>>
>>> "Multiple "audience" parameters
>>>
>>>       may be used to indicate that the issued token is intended to be
>>>
>>>       used at the multiple audiences listed.  The "audience" and
>>>
>>>       "resource" parameters may be used together to indicate multiple
>>>
>>>       target services with a mix of logical names and physical
>>>
>>>       locations.“
>>>
>>>
>>>
>>> And in the end the client may add some scope values to the „meal“, which
>>> brings us to
>>>
>>>
>>>
>>> „Effectively, the requested access rights of the
>>>
>>>    token are the cartesian product of all the scopes at all the target
>>>
>>>    services."
>>>
>>>
>>>
>>> I personally would suggest to drop support for multiple audience and
>>> resource parameters and make audience and resource mutual exclusive. I
>>> think this is sufficient and much easier to implement.
>>>
>>>
>>>
>>> kind regards,
>>>
>>> Torsten.
>>>
>>>
>>>
>>>
>>>
>>> Am 11.01.2017 um 20:04 schrieb Brian Campbell <
>>> bcampbell@pingidentity.com>:
>>>
>>>
>>>
>>> Draft -07 of "OAuth 2.0 Token Exchange" has been published. The primary
>>> change in -07 is the addition of a description of the relationship between
>>> audience/resource/scope, which was a request or comment that came up during
>>> the f2f meeting in Seoul.
>>>
>>> Excerpted from the Document History:
>>>
>>>    -07
>>>
>>>    o  Fixed typo (desecration -> discretion).
>>>    o  Added an explanation of the relationship between scope, audience
>>>       and resource in the request and added an "invalid_target" error
>>>       code enabling the AS to tell the client that the requested
>>>       audiences/resources were too broad.
>>>
>>> ---------- Forwarded message ----------
>>> From: <internet-drafts@ietf.org>
>>> Date: Wed, Jan 11, 2017 at 12:00 PM
>>> Subject: [OAUTH-WG] I-D Action: draft-ietf-oauth-token-exchange-07.txt
>>> To: i-d-announce@ietf.org
>>> Cc: oauth@ietf.org
>>>
>>>
>>>
>>> A New Internet-Draft is available from the on-line Internet-Drafts
>>> directories.
>>> This draft is a work item of the Web Authorization Protocol of the IETF.
>>>
>>>         Title           : OAuth 2.0 Token Exchange
>>>         Authors         : Michael B. Jones
>>>                           Anthony Nadalin
>>>                           Brian Campbell
>>>                           John Bradley
>>>                           Chuck Mortimore
>>>         Filename        : draft-ietf-oauth-token-exchange-07.txt
>>>         Pages           : 31
>>>         Date            : 2017-01-11
>>>
>>> Abstract:
>>>    This specification defines a protocol for an HTTP- and JSON- based
>>>    Security Token Service (STS) by defining how to request and obtain
>>>    security tokens from OAuth 2.0 authorization servers, including
>>>    security tokens employing impersonation and delegation.
>>>
>>>
>>> The IETF datatracker status page for this draft is:
>>> https://datatracker.ietf.org/doc/draft-ietf-oauth-token-exchange/
>>>
>>> There's also a htmlized version available at:
>>> https://tools.ietf.org/html/draft-ietf-oauth-token-exchange-07
>>>
>>> A diff from the previous version is available at:
>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-oauth-token-exchange-07
>>>
>>>
>>> Please note that it may take a couple of minutes from the time of
>>> submission
>>> until the htmlized version and diff are available at tools.ietf.org.
>>>
>>> Internet-Drafts are also available by anonymous FTP at:
>>> ftp://ftp.ietf.org/internet-drafts/
>>>
>>> _______________________________________________
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>>>
>>>
>>>
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>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
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>>> https://www.ietf.org/mailman/listinfo/oauth
>>>
>> --
>>
>> Nat Sakimura
>>
>> Chairman of the Board, OpenID Foundation
>>
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>>
>>
>
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