[OpenID] DISCUSSION relating to OpenID Discovery 2.1

[Peter Williams]

The main problem I have is ...you are changing the character of XRDS (and XRI 2.0 resolution).

 In 1, you are turning metadata discovery into a authorization/control framework. Won't be long before you will want a "#include QXRI" line in the XRDS, that imports XRDs from a superior policy authority, and require the XRI client resolver to now to "augment" the XRDs with those from the control authority. If OpenID needs an policy-based authorization framework, let's consider that in its own right (and there is LOTS AND LOTS of previous work to draw on). Let's not break the (nicely working) metadata model, tho.

In 2, why doesn't XRI already do exactly what you want? Surely, the intelligence you want is in the query syntax, and that is precisely what XRI resolution gives you? The notion that one discovery agent would proxy to n other discovery agents based on criteria from the resolution request seems important (and, again, what other sso discovery protocols already do).

In 3, what is wrong with the XRI extension model? It seems to do exactly what you want.

Now I can see an argument that just as folk could not typically adopt/implement the X.500 DAP query model, but could adopt simpler queries expressed  in simplified ldap urls, so we might need to make a simplified XRI resolver based on lxri:// urls... building on the momentum that wants to simply parse an XRDS stored in a static file (rather than a full-power XRDS stream generated  as a result of resolving an XRI query seeking metadata from the i-broker network)

If 2 and 3 above were expressed in terms of: here is the lightweight profile of XRI tuned to those 3 purposes, and its carefully tuned to be easy to program...that might fly as a work item. Its taking the  current design and simply making it easier to adopt, focusing on




From: general-bounces at openid.net [mailto:general-bounces at openid.net] On Behalf Of David Fuelling
Sent: Monday, December 29, 2008 6:25 AM
To: specs at openid.net; general at openid.net List
Subject: [OpenID] DISCUSSION relating to OpenID Discovery 2.1

Not sure if this made it through to everyone due to the mail list malfunction, so resending just in case.

david
---------- Forwarded message ----------
From: David Fuelling <sappenin at gmail.com<mailto:sappenin at gmail.com>>
Date: Fri, Dec 26, 2008 at 6:58 PM
Subject: DISCUSSION relating to OpenID Discovery 2.1
To: "specs at openid.net<mailto:specs at openid.net>" <specs at openid.net<mailto:specs at openid.net>>, "general at openid.net<mailto:general at openid.net> List" <general at openid.net<mailto:general at openid.net>>


All,

I'd like to propose that the following ideas be considered as discussion points in the OpenID 2.1 Discovery WG.  I've updated the OpenID 2.1 Discovery WG wiki page<http://wiki.openid.net/Working_Groups%3AOpenID_Discovery> to reflect these ideas, and have provided two very rough-draft proposals (currently formulated as extensions) to juice up the dialog.  The ideas are summarized below -- I'd be curious to hear any and all feedback.

Thanks!

David

 1.  Enabling two (or more) headed OP authentication
The idea here is to allow an end-user to specify two (or more) OP's in the <Service> portion of their XRD so that an RP MUST receive auth assertions from both OP's before granting access to protected resources.  See a rough-draft idea proposal here: OP MultiAuth<http://wiki.openid.net/OP-MultiAuth>.  XRI Resolution 2.0 seems to currently prohibit this by default per section 4.3.3: "If two or more instances of the same element type have identical priority attribute values (including the null value), the consuming application SHOULD select one of the instances at random. This consuming application SHOULD NOT simply choose the first instance that appears in XML document order."  Thus, in order to indicate to the RP that both OP URI's should be used at the same time, an aditional <Type> element is used to signify that identical priority URI's should be used together for the purposes of OpenID Auth.
 2.  OP Delegation based upon various characteristics of an OpenID transaction
The idea here is to allow an end-user to delegate authority over a particular OpenID Identifier to divergent OpenID Providers (OP's), depending on certain characteristics of a Relying Party and/or certain characteristics of an OpenID transaction.  For example, an Identifier might specify a different authoritative OP depending on the OpenID-related Service being employed (e.g., OpenID 2.0, OAuth, or others); the RP Domain (*.example.com<http://example.com>); or a pre-defined service Class (e.g., one OP for single-factor auth, and another OP when two-factor Auth is required).   By providing OpenID Identifiers with the ability to specify multiple OP's based on particular characteristics of each OpenID transaction, end-users will be able to utilize the best OP for any particular OpenID transaction as they see fit (i.e., more control in the hands of the user).  See a rough-draft here: OP Delegation<http://wiki.openid.net/OP-Delegation>.
 3.  Discovery Extensions
The OpenID Discovery specification should define ways for discovery to be extended by other services.  For example, the OAuth+OpenID specification may want to peform discovery in slighly different ways than regular OpenID Auth 2.1 does.  Likewise, ideas numbers 1 and 2 above could be implemented as extensions to Discovery instead of being included in the main 2.1 Discovery specification.

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