[OpenID] About Facebook, MySpace and OpenID

Peter Williams pwilliams at rapattoni.com
Sun Apr 5 03:29:33 UTC 2009


If I'm an RP taking authenticated comments from a google subscriber for the first time and the user denies the release of the optional email attribute, is there any way for the user to release it the next time s/he attempts to post a comment?

i.e. depending on the nature of the  comment or the thread, the user may wish  to release or not release the email identifier (to signal that followup email dialog is available, or to receive events that the comments received followup). Lets assume that the site processing the comments does not maintain an account for the commenting user.

From: general-bounces at openid.net [mailto:general-bounces at openid.net] On Behalf Of Breno de Medeiros
Sent: Saturday, April 04, 2009 6:38 PM
To: Deron Meranda
Cc: general; John Bradley
Subject: Re: [OpenID] About Facebook, MySpace and OpenID


It is not true that you need to request all your attributes for the Google OP or else you will be locked out. If you add a request for a new attribute we will prompt the user to authorize and then send it.  That also happens if the value of the attribute changed since the user approved (re-prompt and send).
On Apr 3, 2009 9:35 PM, "Deron Meranda" <deron.meranda at gmail.com<mailto:deron.meranda at gmail.com>> wrote:

On Fri, Apr 3, 2009 at 11:08 PM, Andrew Arnott <andrewarnott at gmail.com<mailto:andrewarnott at gmail.com>> wrote:
> ... All the RPs are upgrading their email requests to required

> so that they work with Google.  Apparently they really wanted email and they > were getting it unt...
Maybe its useful to think about attributes other than email to see
where "optional" perhaps makes more sense.

Consider a possible Time Zone attribute (yes SReg has this).  This is a case
where it is easier to see what an RP might mean by "optional" -- that if the
OP can provide it it wants it; but if not, the RP still wants the authentication
to proceed and not to fail, because it can deal easily enough with not
getting the time zone.

It could also be argued that the OP *should* ask the user which optional
attributes it wants to give.  You might not think time zone is important
enough to ask the user for permission; unless perhaps your time zone
happened to be America/Havana for example and you didn't want this
RP to know you're in Cuba.

I can see Google's perspective on this; and it is a combination of
trying to make a simple UI for non-technical users (which we all
agree is something OpenID desperately needs), as well as the
spec being somewhat silent on what its expectations are for the
OP and RP.


However, at this point, with Google's current interpretation, there is
effectively no utility in having optional attributes.  The distinction is
made meaningless.  And since we don't want RP's to special-case per
OP; then effectively, in practice today anyway, it is pointless for
OpenID AX to pretend there is an optional/required dimension.

Now one can argue that Google is right and the spec was trying to
make two categories when only one made sense; or that Google is
wrong and OPs should definitely treat optional attributes differently
than required ones.  I'm not sure which is correct; but I do think
that the spec should be made very clear one way or the other.
Because if the behavior is left up to the OP, as Google has done, then
the spec is made pointless in practice and its all just unnecessary
noise words.


I would say, another thing that Google does that may play into all
this is that they don't always send AX attributes back at all.  If the
RP and OP have communicated before concerning a certain
identity; then the RP may actually get no attributes whatsoever
on subsequent interactions (Google assumes that the RP will
remember these attributes the first time, which means that in
practice the RP will be forced to remember these attributes).

This also coerces the RP to try to request ALL the attributes it thinks
it might ever need the very first time it interacts with Google.  And since
it also using is directed identity (where the RP doesn't know the identity
before hand), this effectively means that the RP is going to have to
request all the possible AX attributes it might ever desire for any user,
effectively as a *requred* attribute, on every single request!  Because if
it guesses wrong and decides not to ask for a particular attribute even
once, it may then be locked out of ever getting that attribute in the future.

This makes it very hard to implement an RP.  Either it asks for too
many attributes, and the authentication fails because the user doesn''t
want to return ALL of them (or Google doesn't support a hypothetical
Time Zone AX attribute and treats optional as-if required so it fails).
--  Or on the other hand the RP doesn't ask for enough attributes; but
then has to live with never being able to ask for them in the future when
it later decides it does want to know them.

And the directed identity on top of this means the RP has to make this
difficult choice just once per OP, rather than a finer grained per identity.
I think this existing behavior, although defensible from Google's
perspective; pretty much renders a good portion of the AX spec
completely useless.

Either an RP is never going to use AX at all because it doesn't want
to risk causing an authentication to fail; or an RP is always going to
request as many attributes as possible all as required (even if it
doesn't need them right now), because it doesn't want to miss out on
it's one chance to get that information the first time.
--
Deron Meranda
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