[OpenID] Too many providers... and here's one reason

Tue Sep 16 15:58:59 UTC 2008

One way of getting the public key would be to include it in the  
assertion and have the cert signed by a higher, trusted party.  
(typical PKI)

Unless you use the existing PKI, I don't know of a best practice for  
binding domains/URLs to public keys. (there are lots of ways to do it,  
but what is "best practice"?)

Personally, I'd like to see a 'standard way' to do it in OpenID that  
did NOT use existing PKI. Then we could use PK crypto for verifying  
OpenID message signatures and move away from managing pair wise keys  
between RP and OP. Currently this is a pipe dream of course. :-)

-- Dick

On 16-Sep-08, at 8:22 AM, Andrew Arnott wrote:

> I just love a good topic to get the creative juices flowing from so  
> many brainy people.  Thanks all for your ideas.
>
> Regarding George's OP identity assertion w/ AX membership  
> attribute... How could Org XYZ sign the attribute so that coming  
> from some OP it would be a verifiable?  Regarding this loose trust  
> relationship between the OP and Org XYZ, what would that constitute?
>
> The few RPs that would be interested in my membership can have  
> specially crafted AX fetch requests, no problem.  But these RPs need  
> to be able to work against whatever OP the authenticating user  
> happens to choose.  If only a few OPs might support these signed AX  
> attributes that's fine, as long as the user has a choice and there  
> is no strong affiliation between OP, RP and Org.
>
> I wonder if Org could assert my membership with a signed, encoded  
> string, including my claimed id whatever that may be, and I take  
> that encoded string and AX-store it myself to my arbitrary OP.  Then  
> any AX-fetch (with my permission) would retrieve that and the RP  
> could check the signature.  The only thing remaining in my mind is  
> how the RP could verify the signature.  Can an ordinary public HTTPS  
> server cert on Org.com be used to verify a signature if it is signed  
> the right way?  Or is there some other way to do that?
>
> On Tue, Sep 16, 2008 at 6:26 AM, George Fletcher <gffletch at aol.com>  
> wrote:
> Per Dick's response earlier in the thread, I don't see why using an  
> OP of my choice with a third party asserted attribute of my  
> membership in org XYZ isn't sufficient to meet this use case.
>
> Basically, I'd use my preferred OP and request the organization to  
> provide a signed attribute of my membership in org XYZ. Then when I  
> log into the RP (with the OP of my choice), it can request this  
> attribute and I can choose to provide it (or not) at time of  
> authentication.
>
> This should be completely doable with the existing OpenID 2.0 and  
> Attribute Exchange specs. Is the issue what Peter mentioned that  
> there aren't many AX supporters right now?
>
> Of course, there will have to be a "trust relationship" between org  
> XYZ and my preferred OP, but I don't see that trust as any deeper  
> than the "trust relationship" between and RP and an OP.
>
> Thanks,
> George
>
> Andrew Arnott wrote:
> You're affirmative action example is well taken.  Obviously if an OP  
> is the best solution we should go with it.  But just imagine what  
> all these spoons of sugar are going to do to me...
>
> Suppose I'm a member of 15 organizations (that's conservative)  
> between my professional, social, personal lives.  Some RP could be  
> interested in providing specialized services if I am a member of Org  
> XYZ.  Another RP may offer premium services if I am a member of Org  
> ABC.
>
> Now if every org I am a member of became an OP, then my identity  
> XRDS file now has at least 15 providers listed.  Powerful, perhaps.   
> Dangerous: yes!!!  If OpenID's weakness already was that if an OP  
> was compromised then all Identifiers that allow that OP's assertions  
> are now compromised, then that weakness is proportional to the  
> number of OPs that are listed in my XRDS file.  I for one do NOT  
> want 15 Providers listed in my XRDS file.  There was a time I  
> thought more was better, and to date I have some 5-6 OPs listed, but  
> I've considered narrowing that down to just 2-3 to decrease my risk  
> surface area.
>
> Using OAuth as a post-authentication step of confirming membership  
> is an interesting idea and should work.  In the end, whether we use  
> OpenID or OAuth, it seems we're mixing authentication and  
> membership, or authorization and membership, in order to just get  
> membership.  Too bad there's not just a way to get "membership".
>
> Yes, InfoCard managed cards solve this problem, although not as  
> implicitly as I'd like.  I'm hoping OpenID can have a solution of  
> its own.
>
> On Mon, Sep 15, 2008 at 5:12 PM, Eran Hammer-Lahav <eran at hueniverse.com 
>  <mailto:eran at hueniverse.com>> wrote:
>
>    This is like applying affirmative action to cooking. "This cake
>    calls for two spoons of sugar but we don't have enough people
>    using lard in cakes, so I am going to use it instead..."
>
>    Looks like they want to use OpenID as an assertion verification
>    protocol, allowing them to confirm that a given user is in fact a
>    member of their organization. If all they want to do is assert the
>    claim, they can use both OAuth and OpenID, each with a different
>    set of extra features. If they use OpenID, a side-effect of this
>    will turn them into an Identity Provider, but if this is not their
>    intention, they should not use that identifier internally, but
>    instead accept OpenID.
>
>    In other words, they should be an OP for assertion verification,
>    and RP for site login.
>
>    EHL
>
>
>
>    On 9/15/08 4:45 PM, "Andrew Arnott" <andrewarnott at gmail.com
>    <http://andrewarnott@gmail.com>> wrote:
>
>        I just spoke with an organization that wants to become a
>        Provider so that other RP web sites can specifically tell if
>        the logging in user is a member of this organization by
>        whether their OpenID Identifier was asserted by that org's OP.
>        Ideally, I'd like this org to choose to be an RP instead of an
>        OP because there are already too many OPs out there and not
>        enough RPs, IMO.
>        How can an RP accept an OpenID Identifier from arbitrary OPs,
>        but at each login determine whether the Identifier represents
>        a user who belongs to a particular Organization?  Basically
>        the Organization needs to send an assertion about the
>        Identifier's membership, but only be willing to do so if that
>        identifier is confirmed as having logged in successfully to
>        that RP.  This would be easy to do if that Org was an OP, but
>        I'm trying to reduce the # of reasons to be an OP.
>
>
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