Re: [OAUTH-WG] Benjamin Kaduk's Discuss on draft-ietf-oauth-jwt-introspection-response-08: (with DISCUSS and COMMENT)

Takahiko Kawasaki <taka@authlete.com> Mon, 02 March 2020 17:53 UTC

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From: Takahiko Kawasaki <taka@authlete.com>
Date: Tue, 3 Mar 2020 02:53:20 +0900
Message-ID: <CAHdPCmNmCGO42KanrFf=gYsbmkSERc0UmgDxEVDrs=Wv-7Rkzw@mail.gmail.com>
To: Torsten Lodderstedt <torsten@lodderstedt.net>
Cc: Torsten Lodderstedt <torsten=40lodderstedt.net@dmarc.ietf.org>, Benjamin Kaduk <kaduk@mit.edu>, oauth-chairs@ietf.org, The IESG <iesg@ietf.org>, oauth <oauth@ietf.org>, draft-ietf-oauth-jwt-introspection-response@ietf.org
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Subject: Re: [OAUTH-WG] Benjamin Kaduk's Discuss on draft-ietf-oauth-jwt-introspection-response-08: (with DISCUSS and COMMENT)
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Do you mean different requests should have the same jti value for better
security?

It is not good that RFC 7662 has chosen "jti" as a property to hold the
identifier for an access/refresh token although the format of introspection
responses is not JWT but just JSON. If the name were, for instance,
"token_id" or something similar, the problem we are discussing now would
not happen.

Because "jti" has a special meaning in JWT and
draft-ietf-oauth-jwt-introspection-response tries to return introspection
responses in JWT format, the problem occurs.

Not only "jti" but also other properties defined in RFC 7662 that have
special meanings in JWT (that is, "jti", "exp", "iat", "nbf", "sub", "aud"
and "iss") may have problems, too. The namespaces should be separated as
you suggested "underlying_access_token", but because not only access tokens
but also refresh tokens may be passed to the introspection endpoint, a
better name should be chosen.

Taka



On Tue, Mar 3, 2020 at 1:55 AM Torsten Lodderstedt <torsten@lodderstedt.net>
wrote:

>
>
> > Am 02.03.2020 um 17:52 schrieb Takahiko Kawasaki <taka@authlete.com>om>:
> >
> > The requirement for "jti" described
> > in draft-ietf-oauth-jwt-introspection-response-08 is problematic.
>
> I think having different jti values for different requests is a security
> risk.