[OpenID] [LIKELY_SPAM]Re: Problems with delegation and directed identity OPs

Sun Nov 9 18:54:48 UTC 2008

Id recommend an openid.net 1000 word tutorial be written on the openid2 delgation model, adressing clearely how its security model is different to openid1.

I've read and reviewed the openid2 spec several times, and had not realized that fundamental delegation processes had changed (from what I saw in the janrain openid1.1 .net code).

Id realized that names and metadata fields had changed...but not that the security model had changed.

I had no idea that an op maintained identity page (with rdf tags, such as that of myopenid) was anything other than a nicety (that could be entirely eliminated).

________________________________
From: Andrew Arnott <andrewarnott at gmail.com>
Sent: Saturday, November 08, 2008 5:19 PM
To: Martin Atkins <mart at degeneration.co.uk>
Cc: OpenID List <general at openid.net>
Subject: [LIKELY_SPAM]Re: [OpenID] Problems with delegation and directed identity OPs

Reverting back to OpenID 1.1 style of delegation would break unsolicited assertions when the OP is asserting a delegated Identifier.  I thought of another scenario or two that would break as well but I can't think of them at the moment...

On Sat, Nov 8, 2008 at 12:05 AM, Martin Atkins <mart at degeneration.co.uk<mailto:mart at degeneration.co.uk>> wrote:

This seems similar to what happened with clavid.com<http://clavid.com>. When I tested their OP, they would accept OpenID 2.0 requests but always respond with 1.1 responses. (They may have since fixed this.)

The upshot of this was that the OpenID 1.1 responses didn't include openid.claimed_id because that argument didn't exist in OpenID 1.1, so things broke.

There is scope for a careless OP to break delegation by failing to pass through openid.claimed_id as given. This was a concern I had when we added that argument in OpenID 2.0; in 1.1, it was the RP's responsibility to figure out how to maintain that state, and so some RPs did it by adding stuff to openid.return_to in the request and others maintained state at the RP server, but either way it was opaque to the OP and passed through correctly unless the OP did something really bizarre.

I wonder if it would be a good idea to revert to the previous approaches for maintaining the delegation state at the RP, since clearly a faulty OP can break delegation with 2.0 as currently specified. I'm concerned that as we currently stand some 2.0-compatible libraries will be preserving this state in a 1.1-compatible way and thus will work correctly with Google's OP, while others will be relying on openid.claimed_id and break. I know that Net;:OpenID::Consumer for Perl relies on openid.claimed_id in 2.0 mode, but if that differs from everyone else's implementations I would consider making it do it the 1.1 way in all cases in order to be resiliant to broken OPs.

Andrew Arnott wrote:
So I whipped up a delegated claimed identifier for Google.  And guess what?! Google's OP is buggy.

This is my delegated OpenID page that delegates to Google's OP:
http://nerdbank.org/RP/rpgoogle.html

It's magic contents are:
<link rel="openid2.provider" href="https://www.google.com/accounts/o8/ud"/>
<link rel="openid2.local_id" href="https://www.google.com/accounts/o8/id?id=AItOawkBReSGLLy2neuRSMQEz7G8mWH311s8_FU"/>

This works just like any other delegated thing.  Since Google provides pair-wise unique identifiers, I had to first log in to nerdbank.org/RP<http://nerdbank.org/RP> <http://nerdbank.org/RP> using google directly, find out what identifier Google assigned for me at that RP, and then stick that into the above local_id field.  Then this delegated page will /only/ work against that RP.

Or at least that's what should happen.  In actuality Google changes the claimed_id though it shouldn't.  This is what it asserts:

ClaimedIdentifier: https://www.google.com/accounts/o8/id?id=AItOawkBReSGLLy2neuRSMQEz7G8mWH311s8_FU
ProviderLocalIdentifier: https://www.google.com/accounts/o8/id?id=AItOawkBReSGLLy2neuRSMQEz7G8mWH311s8_FU
ProviderEndpoint: https://www.google.com/accounts/o8/ud
OpenID version: 2.0

And this is what was discovered at the delegated identity page:

ClaimedIdentifier: http://nerdbank.org/RP/rpgoogle.html
ProviderLocalIdentifier: https://www.google.com/accounts/o8/id?id=AItOawkBReSGLLy2neuRSMQEz7G8mWH311s8_FU
ProviderEndpoint: https://www.google.com/accounts/o8/ud
OpenID version: 2.0

The ClaimedIdentifier has been tampered with.  This Google's OP should note that the auth request was with its local_id but a 3rd party claimed_id and preserve the claimed_id so that delegation works.  They don't, and delegation breaks.

So you see, it's not that they use directed identity that breaks delegation.  It's that their OP doesn't preserve the openid.claimed_id parameter.  I'm not sure if this is a strict contradiction to the spec, but it breaks scenarios, which stinks.
I'll send this over to the Google folks and see what they have to say.

On Fri, Nov 7, 2008 at 7:17 PM, Andrew Arnott <andrewarnott at gmail.com<mailto:andrewarnott at gmail.com> <mailto:andrewarnott at gmail.com<mailto:andrewarnott at gmail.com>>> wrote:

    From the spec:

   Value: (optional) The Claimed Identifier.

   "openid.claimed_id" and "openid.identity" SHALL be either both
   present or both absent. If neither value is present, the assertion
   is not about an identifier, and will contain other information in
   its payload, using extensions (Extensions).

   So you can't include one without the other.  And having neither
   doesn't provide any authentication at all.  Delegation /should/
   work, if you had an openid identity page with a openid2.local_id tag
   that was exactly the opaque RP-specific identifier that Google would
   assign the RP that you are trying to log into.  That would mean
   you'd need a separate delegate page for every single RP you log
   into... but it's theoretically possible.  It would just be a
   maintenance nightmare. It would be interesting to test just to see
   if Google actually implemented the spec correctly to handle
   /non/-directed identity scenarios.

   On Fri, Nov 7, 2008 at 5:40 PM, Breno de Medeiros <breno at google.com<mailto:breno at google.com>
   <mailto:breno at google.com<mailto:breno at google.com>>> wrote:

       On Fri, Nov 7, 2008 at 4:48 PM, Allen Tom <atom at yahoo-inc.com<mailto:atom at yahoo-inc.com>
       <mailto:atom at yahoo-inc.com<mailto:atom at yahoo-inc.com>>> wrote:
        > Deron Meranda wrote:
        >> Of course, from an OP usability perspective, it's not
       exactly straight
        >> forward for somebody to determine their actual Yahoo
       identity(-ies),
        >> although it is possible.
        >>
        > We definitely can improve the usability, but you can list
       your Yahoo
        > OpenID identifiers by going to http://openid.yahoo.com and
       clicking on
        > the "OpenID Home link" at the top of the page.
        >
        >> And, just from curiosity, why are the randomly generated URIs
        >> (both Google and Yahoo!) so long?
        > :)
        >
        >> So, the current Google situation makes it almost impossible
       to use delegation!
        >>
        >>
        > Hmm, it does appear that it's impossible for someone to
       delegate their
        > OpenID to Google.

       The OpenID spec says that the op_local is an optional field. I think
       in practice libraries set identity=claimed_id in this case. I assume
       it is then unspecified how the OP validates that the user is
       authorized over that URL. That changes nothing from the RP
       perspective, because it always has to depend on the OP to make that
       judgment.

       Bottom line: The fact that the op_local technique is not
       available for
       usage with the Google OP does not mean that it cannot support
       delegation.

        >
        > Allen
        >
        >
        > _______________________________________________
        > general mailing list
        > general at openid.net<mailto:general at openid.net> <mailto:general at openid.net<mailto:general at openid.net>>

        > http://openid.net/mailman/listinfo/general
        >

       --
       --Breno

       +1 (650) 214-1007 desk
       +1 (408) 212-0135 (Grand Central)
       MTV-41-3 : 383-A
       PST (GMT-8) / PDT(GMT-7)
       _______________________________________________
       general mailing list
       general at openid.net<mailto:general at openid.net> <mailto:general at openid.net<mailto:general at openid.net>>

       http://openid.net/mailman/listinfo/general

------------------------------------------------------------------------

_______________________________________________
general mailing list
general at openid.net<mailto:general at openid.net>
http://openid.net/mailman/listinfo/general