Subject: [OAUTH-WG] [Technical Errata Reported] RFC6749 (3780)

From: RFC Errata System <[email-masked]>
Date: Mon, 4 Nov 2013 08:10:54 -0800 (PST)

The following errata report has been submitted for RFC6749,
"The OAuth 2.0 Authorization Framework".

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You may review the report below and at:
http://www.rfc-editor.org/errata_search.php?rfc=6749&eid=3780

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Type: Technical
Reported by: Torsten Lodderstedt <[email-masked]>

Section: 3.2.1

Original Text
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A client MAY use the "client_id" request parameter to identify itself
   when sending requests to the token endpoint.

Corrected Text
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A public client MAY use the "client_id" request parameter to identify 
itself when sending requests to the token endpoint.

Notes
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The current text may mislead confidential clients to sent their client_id in the request body in addition to their client_id and client_secret in the BASIC authz header. This leads to unnecessary duplication and ambiguities. 

There has been consensus on the list that the intention of this sentence was to advise _public_ clients to identity themselves towards the token endpoint in order to mitigate substitution attacks and allow for logging. Confidential clients need to authenticate anyway, this sentence should be narrowed down to public clients only. 

see http://www.ietf.org/mail-archive/web/oauth/current/msg12005.html

This issue was discovered in the course of the OpenID Connect Interop testings.

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RFC6749 (draft-ietf-oauth-v2-31)
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Title               : The OAuth 2.0 Authorization Framework
Publication Date    : October 2012
Author(s)           : D. Hardt, Ed.
Category            : PROPOSED STANDARD
Source              : Web Authorization Protocol
Area                : Security
Stream              : IETF
Verifying Party     : IESG