[Openid-specs-ab] OIDC Session Management and third party cookie blocking

[Jake Feasel]

While this concern is important, if we follow it through completely it
kills the entire auth code grant for the same reasons. Looking at it from
the browser point-of-view, the auth code grant is just some redirection
across domains involving the transmission of an opaque "code" generated by
the OP back to the RP, followed by an additional call from the RP to the OP
passing it back; who is to say that this code isn't used for tracking users
across sites?

"The browser people don’t seem to care about that at the moment." - There
is a good reason why the privacy-conscious should not be opposed to this
general technique (both the auth code and the proposed session check
grants). Both grants can only work in a third-party cookie blocking
environment if the browser is redirected through the OP at the top-level
(i.e. as a first party interaction). I believe this is the critical point
that shifts the usage from "nefarious" to "legitimate".

Put another way - if a privacy-abusing marketing company wanted to try to
copy this pattern for their own nefarious purposes, they would have to
require every page they advertise on to have a top-level redirect for all
visitors through their own domain and back again (passing the requisite
tracking id back in the URL). I feel like this extremely obtrusive pattern
would not be acceptable for most pages that just want to show ads - it's
only acceptable in the case of authentication because the site and the user
have very tangible benefits from the interruption in flow associated with
logging in.

I think we are on safe ground here, in terms of what patterns are likely to
be shut down in the future. As such I would like to continue with this
"session_check" grant proposal.

Thanks



On Wed, Aug 10, 2022 at 3:25 AM Mischa Salle via Openid-specs-ab <
openid-specs-ab at lists.openid.net> wrote:

> On Tue, Aug 09, 2022 at 06:39:27PM +0000, Nicole Roy via Openid-specs-ab
> wrote:
> > My concern would be that a browser employing “Intelligent Tracking
> Prevention” would see the POST of the SID as tracking and prevent it. Of
> course, doing so breaks all sorts of other things, but the browser people
> don’t seem to care about that at the moment.
>
> probably would have the same problems with "nonce" and "state" then?
> Plus makes one wonder whether these three could not have been a single
> parameter?
>
> Mischa
>
> > > On Aug 2, 2022, at 4:30 PM, Jake Feasel via Openid-specs-ab <
> openid-specs-ab at lists.openid.net> wrote:
> > >
> > > This topic has been raised before, but based on the traffic from this
> list it seems to not be going anywhere. I would like to revive it.
> > >
> > > I had a quick talk at Identiverse this year covering the OIDC Session
> Management draft spec, in particular my take on the upcoming
> "Cookiepocalypse" and how it will render the current draft completely
> obsolete. You can see my slides here:
> https://docs.google.com/presentation/d/1uU3KvK6ayTpjB2OEmrSqQnUdJDPSdfxxetJrks1czvI/edit#slide=id.g11aa5093f19_0_63
> <
> https://docs.google.com/presentation/d/1uU3KvK6ayTpjB2OEmrSqQnUdJDPSdfxxetJrks1czvI/edit#slide=id.g11aa5093f19_0_63
> >
> > >
> >
> > [snip]
> >
> > > The OP will include the "sid" claim (as defined in the Front and
> Back-channel logout drafts) as a claim in the id_token used in an auth_code
> grant. This "sid" value will be included in a POST request to the "token"
> endpoint on the OP on a periodic basis (likely prompted from user activity
> within the RP). It would like something like so (note the absence of a
> cookie in this request):
> > >
> > >   POST /token HTTP/1.1
> > >   Host: server.example.com <http://server.example.com/>
> > >   Content-Type: application/x-www-form-urlencoded
> > >   Authorization: Basic czZCaGRSa3F0MzpnWDFmQmF0M2JW
> > >
> > >   grant_type=session_check&sid=1234xyz
> > >
> > > The response code from this could be a 401 if the sid is not
> associated with a valid OP session, or 200 if it is. The response body in
> the case of a 200 could include a new id_token with updated session claims
> (to provide better context for when the session expires or if other
> important details about the session change).
> > >
> >
> > [snip]
> >
>
>
>
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>
>
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