This is a convincing use in support of the multiple assertions.
My understanding is that in the use case the two assertions provide the 
different statements of the different issuers regarding the same subject (the 
person seeking a parking permit). Is there a use case that requires multiple 
assertions regarding different subjects?

Zachary

________________________________
From: oauth-boun...@ietf.org [mailto:oauth-boun...@ietf.org] On Behalf Of 
Anthony Nadalin
Sent: Friday, August 20, 2010 2:19 PM
To: Chuck Mortimore; Eran Hammer-Lahav; Brian Campbell
Cc: oauth
Subject: Re: [OAUTH-WG] more than one assertion?

So the UK Government Gateway project is a concrete use case. The use case for 
the UK government is that the government has many assertion providers; this is 
due to both legal and historical reasons. The first assertion provider is UK 
Department of Works and Pension (DWP), the second one is Department of Motor 
Vehicles and the third is the Department of Revenue (and so on ...). A citizen 
may need and assertion from each one of these government departments attesting 
to various things. A person wants a parking permit, so DWP and Department of 
Motor Vehicles are involved; DWP is the authoritative source of address and DMV 
is the authoritative source of vehicle information. So in order to obtain a 
parking permit, I have to live on the street that I obtain the parking permit 
for and I also need to own the vehicle for which I'm obtaining the parking 
permit. So these 2 assertions under different subject identifiers would have to 
be submitted to obtain the parking permit. So there has to be a way to carry 
the 2 assertions to obtain the token to get the parking permit.


From: oauth-boun...@ietf.org [mailto:oauth-boun...@ietf.org] On Behalf Of Chuck 
Mortimore
Sent: Thursday, August 12, 2010 10:24 AM
To: Eran Hammer-Lahav; Brian Campbell
Cc: oauth
Subject: Re: [OAUTH-WG] more than one assertion?

Personally, I'd first like to see more concrete use-cases of how multiple 
assertions are going to be used in practice.   Tony alluded to some abstract 
use-cases, but fuller descriptions would probably help everyone out.

-cmort


On 8/10/10 9:15 AM, "Eran Hammer-Lahav" <e...@hueniverse.com> wrote:
WFM.

> -----Original Message-----
> From: Brian Campbell [mailto:bcampb...@pingidentity.com]
> Sent: Tuesday, August 10, 2010 9:03 AM
> To: Eran Hammer-Lahav
> Cc: oauth
> Subject: Re: [OAUTH-WG] more than one assertion?
>
> To be honest, I somehow overlooked that particular text - my mistake and
> apologies. Reading it again, it probably does preclude parameters from
> repeating, however, I can see some room for varied interpretations as to if
> that's a strong normative requirement or a looser suggestion about an error
> code that could be used in that circumstance.
>
> Perhaps it could be made more clear by adding some wording about it to the
> end of the first part of sections 3&4 where it says: "Parameters sent without
> a value MUST be treated as if they were omitted from the request.  The
> authorization server SHOULD ignore unrecognized request parameters."?
>
> That said, does it make sense to relax the ban on repeating parameters in
> some situations, like for the assertion parameter, to facilitate
> easy encoding of multiple assertions?   Anthony (Tony?) Nadalin
> suggested that multiple assertions might be a common use case and I think
> allowing for that via repeating assertion parameters is a cleaner and more
> reusable way to do it.
>
> The text at the bottom of section for could say something like:
>
> "Parameters sent without a value MUST be treated as if they were omitted
> from the request.  The authorization server SHOULD ignore unrecognized
> request parameters.  Parameters MUST NOT repeat unless otherwise noted
> in the parameter definition."
>
> Then in 4.1.3. the assertion parameter could be something like this:
>
>   "assertion
>          REQUIRED.  The assertion(s).  This parameter MAY be repeated in the
> request,  if more than one
>           assertion is needed for the access grant"
>
>
> Obviously Eran could improve on the actual text but hopefully that gets the
> concept across?
>
>
>
> On Mon, Aug 9, 2010 at 10:43 PM, Eran Hammer-Lahav
> <e...@hueniverse.com> wrote:
> > Do we need to clarify 4.3.1 "repeats a parameter" description for
> "invalid_request" error code does not preclude parameters from repeating?
> I'm not sure.
> >
> > EHL
> >
> >> -----Original Message-----
> >> From: oauth-boun...@ietf.org [mailto:oauth-boun...@ietf.org] On
> >> Behalf Of Brian Campbell
> >> Sent: Monday, August 09, 2010 12:34 PM
> >> To: oauth
> >> Subject: [OAUTH-WG] more than one assertion?
> >>
> >> The question of allowing for multiple assertions in the SAML profile
> >> came up recently.  See http://www.ietf.org/mail-
> >> archive/web/oauth/current/msg04068.html and several subsequent
> >> messages in the thread.
> >>
> >> I pushed back on the idea at first due to added complexity.  There
> >> are a number of things that need to be addressed that aren't present
> >> in the single assertion case.   One of the sticker ones, to me, was
> >> how to encode the assertions into the request.   A SAML <Response>
> >> element is a nice container for multiple assertions but using it in
> >> this context seemed awkward at best.  A new schema could be defined
> >> or a special deliminator character could be used but that seems excessive
> and kludgy respectively.
> >>
> >> What about pushing it up into the HTTP layer and allowing for
> >> multiple occurrences of the assertion=XXX parameter in the POST body?
> >> I don't see anything in core OAuth that would necessarily preclude doing
> this.
> >>  It seems cleaner and more lightweight than some of the other options.
> >>  And perhaps it could be a more general (not just SAML) method of
> >> sending multiple assertions in a single assertion grant type request?
> >>
> >> It'd look something like this:
> >>
> >>   POST /token.oauth2 HTTP/1.1
> >>   Host: authz.example.net
> >>   Content-Type: application/x-www-form-urlencoded
> >>
> >>    grant_type=assertion&assertion_type=http%3A%2F%2Foauth.net%2Fa
> sse
> >>    rtion_type%2Fsaml%2F2.0%2Fbearer&assertion=[...1st
> >> assertion...]&assertion=
> >>    [...2nd assertion...]&assertion=[...3nd assertion...]
> >> _______________________________________________
> >> OAuth mailing list
> >> OAuth@ietf.org
> >> https://www.ietf.org/mailman/listinfo/oauth
> >
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