IdP vs OP (WAS: RE: "Editors" Conference Call)

Tue Nov 7 06:25:32 UTC 2006

I want to clear up what I believe are two misconceptions about the proposed
terminology change (both in the specs and across all the OpenID
educational/marketing materials) from "Identity Provider" (IdP) to "OpenID
Provider" (OP). (Note that these are my personal views and may not be shared
by others on the list -- the are offered to help propel the discussion
towards a community consensus.)

1) I don't personally believe there is much difference at all between
"identity provider" (IdP) and "OpenID provider" (OP) -- certainly not enough
to debate. We might even just agree that an OP is what SAML calls an IdP
that uses the OpenID protocol for authentication. That's not at all the
reason why I support the terminology change. The real reason...

2) ...is that in the context of user-centric identity, I have always felt
that the term "identity provider" -- though I fully understand that it goes
back to the start of SAML -- is at least inappropriate and perhaps even
downright misleading.

Why? It's because in a user-centric identity, the OP is fundamentally
********NOT******** (that enough stars for you? ;-) the provider of anyone's
"identity".

This might look like a little thing, but on such little things entire
worldviews rest. 

Let me elaborate. In the last 2 months, I've had numerous conversations with
SAML proponents asking me, "Why is there so much interest in OpenID? It's
just reinventing SAML without a lot of the complexity." And each time I
admit that, to the best of my knowledge, this is largely true.

So why, indeed, is there so much interest in OpenID? I believe it's because
of the trust model. To the best of my knowledge, it is radically different
than the trust model assumed by the majority of use cases which led to SAML
and the Liberty Alliance specs. As Eve Maler of Sun puts it, OpenID supports
"promiscuous federation" -- RPs and OPs that don't know anything at all
about each other. And it doesn't stop there. OpenID also supports OPs that
***have zero control over the user's OpenID identifier***. The OP simply
provides a service for authenticating that a user has control of the OpenID
identifier about which the OP is being queried.

This is a big deal. In fact, the closer you get to it, the bigger it is.

As a result, even though an OP seems to fit the SAML definition of an IdP --
and many technical folks will be very comfortable treating the two as
synonymous -- getting the semantics right to stress who really is in control
of the identity ***right down to the identifier*** is very important.

Whatsmore, I don't think this should or will "drive SAML and OpenID further
apart". In factit could actually help pave the path to convergence: an OP
can be defined as being a SAML IdP that provides identifier authentication
services using the OpenID protocol, which may end out (3.0?) becoming a very
specific set of SAML capabilities.

=Drummond 

-----Original Message-----
From: specs-bounces at openid.net [mailto:specs-bounces at openid.net] On Behalf
Of Recordon, David
Sent: Monday, November 06, 2006 11:46 AM
To: Dick Hardt; John Kemp; Patrick Harding
Cc: specs at openid.net
Subject: IdP vs OP (WAS: RE: "Editors" Conference Call)

I see both sides of this discussion.  I think John is correct that the
role of an OP really is not that different than that of SAML's IdP.  The
difference comes down to the trust model.  I certainly think reputation
networks will exist which rate OPs, RPs, users, etc and will ultimately
be needed for a technologies with "promiscuous trust models" to thrive
in a large scale.

I guess reading more of this is making me question if renaming IdP
really is the best thing to do in OpenID.  I think if anything we all,
as a larger community, should be working to bring OpenID and SAML closer
together versus driving them further apart.

--David

-----Original Message-----
From: specs-bounces at openid.net [mailto:specs-bounces at openid.net] On
Behalf Of Dick Hardt
Sent: Wednesday, November 01, 2006 2:20 PM
To: John Kemp
Cc: specs at openid.net
Subject: Re: "Editors" Conference Call

On 1-Nov-06, at 12:28 PM, John Kemp wrote:
> OK. Just checking. So an IdP/OP can choose whether or not to trust a 
> particular RP, based on some out-of-ban criteria. And an RP can choose

> whether or not to trust the assertions of a particular IdP/OP? OK 
> good.

Technically possible, yes for the RP to decide on an IdP/OP.
Currently, there is no verified RP identity, so the IdP/OP cannot make
that decision.

>> I have not had a chance to wade into that discussion.
>
> I'd highly recommend it when you get the chance.

in my queue :)

>
>>
>>> I suspect the latter case will be unlikely, if OpenID is to be 
>>> successful.
>>
>> And I do not. And that is the big driver why it should be OP instead 
>> of IdP.
>
> I think what you're trying to say is that OpenID won't depend on 
> static trust relationships (like business contracts) between RPs and 
> IdP/ OPs - is that right? In which case, sure, I get that.
>
> But I do think OpenID will depend on there emerging a way of some RP 
> trusting (or not) some IdP (and vice-versa). Whitelists and blacklists

> seem like a scalable and dynamic way of doing that, and would seem to 
> be a reasonable way of minimizing the presence of rogue IdPs. Don't 
> take my word for it though - look at the discussion on security at .

I don't think there should be an OP reputation. I will wade into the
security@ list to discuss.

>> asserted data.
>> The OP is not verifying the accuracy of any of the attributes in 
>> attribute exchange.
>
> A claim by my IdP/OP /might/ be a claim by a third-party, no? And if 
> the IdP/OP makes such a claim on my behalf (and is not under my direct

> control), won't it at least want to verify that the subject of the 
> claim is also the user whose identifier it asserted in OpenID 
> Authentication?

If the OP is making a separate claim about you, then it is not being an
OP at that time.
Perhaps I am missing your point here though.

>
>>
>>>
>>>>
>>>> In OpenID Authentication, there is no trust relationship  
>>>> requirement
>>>> between the IdP and RP., and the only thing the IdP asserts is a
>>>> binding between the user and an identifier (OpenID URL or i-name).
>>>
>>> And on what basis does the OP "assert" this binding to an RP?  
>>> Doesn't
>>> the OP typically "authenticate" that binding, or does it simply  
>>> take the
>>> users identifier on blind faith, and assert away?
>>
>> The OP authenticates the user (how the OP authenticates the user  
>> is out
>> of scope of the spec).
>
> OK - so the user probably maintains an "account" with the OP, very  
> much
> like a user would with an IdP? Unless the user runs her own OP.

The OP has a mechanism to determine which user it is interacting with.
If the user is running her own OP, then there is still an  
authentication process of some kind such as access to the machine.

-- Dick
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