Re: [OAUTH-WG] Fwd: New Version Notification for draft-lodderstedt-oauth-rar-02.txt

Justin Richer <> Thu, 26 September 2019 16:42 UTC

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From: Justin Richer <>
To: George Fletcher <>
CC: Aaron Parecki <>, Torsten Lodderstedt <>, oauth <>
Thread-Topic: [OAUTH-WG] Fwd: New Version Notification for draft-lodderstedt-oauth-rar-02.txt
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Subject: Re: [OAUTH-WG] Fwd: New Version Notification for draft-lodderstedt-oauth-rar-02.txt
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I agree with George that this is a good fit for a security consideration, not a normative requirement. While it’s best to always protect the request data, this isn’t all that much different from having scopes that might leak personal information. Like for example, asking for access to HIV information for a health record. It’s made more explicit and potentially worse by RAR, but it’s far from unique.

This combination of issues is part of why XYZ effectively requires a combination of PAR and RAR for all requests.

— Justin

On Sep 26, 2019, at 9:18 AM, George Fletcher <<>> wrote:

This is a great point about personal information. However, there are uses for authorization_details that don't specifically relate to personal information. Think an enhancement that has language preference, maybe a device identifier. Maybe we can add more text in the security considerations section stating that it's best practice to use PAR for any authorization_details that are considered personal information (PI) or personally identifying information (PII) ?

On 9/26/19 11:02 AM, Aaron Parecki wrote:

Hi Torsten,

Overall I am a fan of a way to provide more structure in authorization
requests, and I'm excited to see this draft, so thanks for that.

I do have some concerns about one aspect of this. Given its clear
intended use as a way to create authorization requests to do things
like transfer money between bank accounts, I don't think it's
appropriate for that kind of data to be sent in the front channel at
all. By encoding a rich authorization request with bank account
numbers and account names in a query string, that opens up several new
opportunities for an attacker to steal private/sensitive information
(browser extensions, proxy servers, etc).

This differs from the plain OAuth authorization request because
traditionally the request does not include any identifying information
about any user or even about the particular transaction. At most, the
request identifies the client and combination of coarse-grained scopes
the client is requesting, none of which can identify a user. However
with the examples provided in this document, as well as many
additional uses of this mechanism, it includes potentially a lot of
identifying information about users including their name, bank account
numbers, and even relationships to other parties (e.g. creditorName).
When the authorization request is sent to the AS in a URL, regardless
of whether it's in plaintext like the simple example here, or signed
as a JWT request, that data is visible to anything that can access the
URL between the user's device and the AS. This seems like a huge
potential for a privacy leak.

I realize this draft currently points to JWT Secured Authorization
Requests (JAR) in several places where these concerns come up. The
problem is that JAR doesn't actually *require* an encrypted JWT, so
the privacy implications aren't accounted for here.

I would much rather see this document require your other recent
submission, Pushed Authorization Requests. Given the privacy
implications, it makes sense to limit the use of rich authorization
requests to pushed authorization requests, so that this rich data is
never made available to intermediaries in the front channel.

If there is a good reason to continue allowing authorization requests
as a GET without the new pushed request step, then at least I would
want to see RAR require encrypted JWTs as described by JAR.

Thanks for considering this!

Aaron Parecki<>

On Sat, Sep 21, 2019 at 7:51 PM Torsten Lodderstedt
<><> wrote:

Hi all,

I just published a draft about ???OAuth 2.0 Rich Authorization Requests??? (formerly known as ???structured scopes???).

It specifies a new parameter ???authorization_details" that is used to carry fine grained authorization data in the OAuth authorization request. This mechanisms was designed based on experiences gathered in the field of open banking, e.g. PSD2, and is intended to make the implementation of rich and transaction oriented authorization requests much easier than with current OAuth 2.0.

I???m happy that Justin Richer and Brian Campbell joined me as authors of this draft. We would would like to thank Daniel Fett, Sebastian Ebling, Dave Tonge, Mike Jones, Nat Sakimura, and Rob Otto for their valuable feedback during the preparation of this draft.

We look forward to getting your feedback.

kind regards,

Begin forwarded message:

Subject: New Version Notification for draft-lodderstedt-oauth-rar-02.txt
Date: 21. September 2019 at 16:10:48 CEST
To: "Justin Richer" <><>, "Torsten Lodderstedt" <><>, "Brian Campbell" <><>

A new version of I-D, draft-lodderstedt-oauth-rar-02.txt
has been successfully submitted by Torsten Lodderstedt and posted to the
IETF repository.

Name: draft-lodderstedt-oauth-rar
Revision: 02
Title: OAuth 2.0 Rich Authorization Requests
Document date: 2019-09-20
Group: Individual Submission
Pages: 16

  This document specifies a new parameter "authorization_details" that
  is used to carry fine grained authorization data in the OAuth
  authorization request.

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at<>.

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