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

Vittorio Bertocci <Vittorio@auth0.com> Thu, 12 March 2020 19:04 UTC

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From: Vittorio Bertocci <Vittorio@auth0.com>
Date: Thu, 12 Mar 2020 12:04:40 -0700
Message-ID: <CAO_FVe5qEz43n=61qbf51P9iO5-N7A+9wJm8xj5f7tZFbeFweA@mail.gmail.com>
To: Torsten Lodderstedt <torsten=40lodderstedt.net@dmarc.ietf.org>
Cc: Aaron Parecki <aaron@parecki.com>, OAuth WG <oauth@ietf.org>
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Subject: Re: [OAUTH-WG] First Draft of OAuth 2.1
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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>gt;:
>
> 
> 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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