Re: [OAUTH-WG] First Draft of OAuth 2.1

Torsten Lodderstedt <torsten@lodderstedt.net> Thu, 12 March 2020 20:57 UTC

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From: Torsten Lodderstedt <torsten@lodderstedt.net>
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Date: Thu, 12 Mar 2020 21:57:11 +0100
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Cc: Vittorio Bertocci <Vittorio=40auth0.com@dmarc.ietf.org>, OAuth WG <oauth@ietf.org>, Torsten Lodderstedt <torsten=40lodderstedt.net@dmarc.ietf.org>
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To: Pedro Igor Silva <psilva@redhat.com>
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Subject: Re: [OAUTH-WG] First Draft of OAuth 2.1
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Then why are you rotating refresh tokens? 

> Am 12.03.2020 um 20:48 schrieb Pedro Igor Silva <psilva@redhat.com>om>:
> 
> 
> A confidential client, as per the `web application` definition in Section `2.1.  Client Types`.
> 
>> On Thu, Mar 12, 2020 at 4:39 PM Torsten Lodderstedt <torsten@lodderstedt.net> wrote:
>> Is that a public client?
>> 
>>>> Am 12.03.2020 um 20:32 schrieb Pedro Igor Silva <psilva@redhat.com>om>:
>>>> 
>>> 
>>> I agree with you and recently, we had to deal with an issue where a `web application` using rotation (as defined by the draft) was having issues to refresh tokens due to multiple concurrent requests at the moment a token is about to expire or already expired. We had to add some controls to deal with concurrency and additional complexity + performance penalties. And for such clients, I was not sure whether or not rotation makes sense.
>>> 
>>>> On Thu, Mar 12, 2020 at 4:05 PM Vittorio Bertocci <Vittorio=40auth0.com@dmarc.ietf.org> wrote:
>>>> Thanks for the clarification, Torsten.
>>>> I believe it's the first time I see use of client credentials positioned as sender constraint; if the intent is saying that confidential clients should use their credentials when redeeming refresh tokens, I am of course in agreement but I think the language should be clearer and state the above explicitly.
>>>> 
>>>> Re: failure frequency, I know of scenarios were the designers added rotation by default, and after a while it was turned to opt in because of the frequency of errors and impact on user experience/call center.
>>>> I really believe that putting this as a MUST is justified only for exceedingly vulnerable situations, like SPAs.
>>>> Native/desktop clients should be free to decide whether they want to opt in without loosing compliance. Just my 2 C
>>>> 
>>>>> On Thu, Mar 12, 2020 at 11:58 AM Torsten Lodderstedt <torsten=40lodderstedt.net@dmarc.ietf.org> wrote:
>>>>> Hi,
>>>>> 
>>>>> sender constraining refresh tokens for confidential client means client authentication + check the binding of the refresh token with the respective client id. I don’t think this is new as RFC6759 already required ASs to check this binding. Assuming backends are generally confidential clients also means no rotation and no cache synchronization needed.
>>>>> 
>>>>> Rotation should be used for frontends, e.g. native apps and only if there is there no other option. If a refresh fails, the app must go through the authorization process again. That’s inconvenient so the question is how often this happens. What I can say, I have never seen customer complaining in several years of operation of ASs with refresh token rotation (including replay detection) for native apps with millions of users.
>>>>> 
>>>>> best regards,
>>>>> Torsten.
>>>>> 
>>>>>>> Am 12.03..2020 um 19:24 schrieb Vittorio Bertocci <Vittorio=40auth0.com@dmarc.ietf.org>rg>:
>>>>>>> 
>>>>>> 
>>>>>> Hey guys,
>>>>>> thanks for putting this together.
>>>>>> I am concerned with the real world impact of imposing sender constraint | rotation as a MUST on refresh tokens in every scenario.
>>>>>> Sender constraint isn't immediately actionable - we just had the discussion for dPOP, hence I won't go in the details here.
>>>>>> Rotation isn't something that can be added without significant impact on development and runtime experiences:
>>>>>> on distributed scenarios, it introduces the need to serialize access to shared caches
>>>>>> network failures can lead to impact on experience- stranding clients which fail to receive RTn+1 during RTn redemption in a limbo where user interaction might become necessary, disrupting experience or functionality for scenarios where the user isn't available to respond.
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>> On Wed, Mar 11, 2020 at 5:28 PM Aaron Parecki <aaron@parecki..com> wrote:
>>>>>>> I'm happy to share that Dick and Torsten and I have published a first
>>>>>>> draft of OAuth 2.1. We've taken the feedback from the discussions on
>>>>>>> the list and incorporated that into the draft.
>>>>>>> 
>>>>>>> https://tools.ietf.org/html/draft-parecki-oauth-v2-1-01
>>>>>>> 
>>>>>>> A summary of the differences between this draft and OAuth 2.0 can be
>>>>>>> found in section 12, and I've copied them here below.
>>>>>>> 
>>>>>>> > This draft consolidates the functionality in OAuth 2.0 (RFC6749),
>>>>>>> > OAuth 2.0 for Native Apps (RFC8252), Proof Key for Code Exchange
>>>>>>> > (RFC7636), OAuth 2.0 for Browser-Based Apps
>>>>>>> > (I-D.ietf-oauth-browser-based-apps), OAuth Security Best Current
>>>>>>> > Practice (I-D.ietf-oauth-security-topics), and Bearer Token Usage
>>>>>>> > (RFC6750).
>>>>>>> >
>>>>>>> >   Where a later draft updates or obsoletes functionality found in the
>>>>>>> >   original [RFC6749], that functionality in this draft is updated with
>>>>>>> >   the normative changes described in a later draft, or removed
>>>>>>> >   entirely.
>>>>>>> >
>>>>>>> >   A non-normative list of changes from OAuth 2.0 is listed below:
>>>>>>> >
>>>>>>> >   *  The authorization code grant is extended with the functionality
>>>>>>> >      from PKCE ([RFC7636]) such that the only method of using the
>>>>>>> >      authorization code grant according to this specification requires
>>>>>>> >      the addition of the PKCE mechanism
>>>>>>> >
>>>>>>> >   *  Redirect URIs must be compared using exact string matching as per
>>>>>>> >      Section 4.1.3 of [I-D.ietf-oauth-security-topics]
>>>>>>> >
>>>>>>> >   *  The Implicit grant ("response_type=token") is omitted from this
>>>>>>> >      specification as per Section 2.1.2 of
>>>>>>> >      [I-D.ietf-oauth-security-topics]
>>>>>>> >
>>>>>>> >   *  The Resource Owner Password Credentials grant is omitted from this
>>>>>>> >      specification as per Section 2.4 of
>>>>>>> >      [I-D.ietf-oauth-security-topics]
>>>>>>> >
>>>>>>> >   *  Bearer token usage omits the use of bearer tokens in the query
>>>>>>> >      string of URIs as per Section 4.3.2 of
>>>>>>> >      [I-D.ietf-oauth-security-topics]
>>>>>>> >
>>>>>>> >   *  Refresh tokens must either be sender-constrained or one-time use
>>>>>>> >      as per Section 4.12.2 of [I-D.ietf-oauth-security-topics]
>>>>>>> 
>>>>>>> https://tools.ietf.org/html/draft-parecki-oauth-v2-1-01#section-12
>>>>>>> 
>>>>>>> I'm excited for the direction this is taking, and it has been a
>>>>>>> pleasure working with Dick and Torsten on this so far. My hope is that
>>>>>>> this first draft can serve as a good starting point for our future
>>>>>>> discussions!
>>>>>>> 
>>>>>>> ----
>>>>>>> Aaron Parecki
>>>>>>> aaronparecki.com
>>>>>>> @aaronpk
>>>>>>> 
>>>>>>> P.S. This notice was also posted at
>>>>>>> https://aaronparecki.com/2020/03/11/14/oauth-2-1
>>>>>>> 
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