Nat, I know you've been an advocate of artifact binding, what are your thoughts 
here?

Cheers,

Brian
___________

Brian Kissel<http://www.linkedin.com/pub/0/10/254>
CEO - JanRain, Inc.
[email protected]
Mobile: 503.342.2668 | Fax: 503.296.5502
519 SW 3rd Ave. Suite 600  Portland, OR 97204

Increase registrations, engage users, and grow your brand with RPX.  Learn more 
at www.rpxnow.com<http://www.rpxnow.com/>

From: Allen Tom [mailto:[email protected]]
Sent: Wednesday, January 27, 2010 3:02 PM
To: Brian Kissel; Andrew Arnott; John Bradley; Breno de Medeiros; specs
Cc: Drebes, Larry; Ellin, Brian
Subject: Re: Problem with nonces and HTTP GET

At least with regards to HuffPo - we ended up removing attributes from the 
request to get under the 2KB url limit, which eliminated the security warning 
since we can return the response via GET instead of POST.

At least in the near term, I'd like to compact AX so that we can squeeze in 
more data - we should be able to do this for AX 1.1. OPs can also implement 
this internal artifact mechanism to switch from HTTPS to HTTP before returning 
the data.

In the longer term, some form of Artifact Binding would probably be better, but 
I guess this would take longer to implement.

Allen



On 1/22/10 10:59 AM, "Brian Kissel" <[email protected]> wrote:
+1 Allen, here's what I get on HuffPo, not very compelling and probably a 
trigger to "Cancel" to most users.  We need to fix this ASAP!

[cid:[email protected]]


Cheers,

Brian
___________

Brian Kissel <http://www.linkedin.com/pub/0/10/254>
CEO - JanRain, Inc.
[email protected]
Mobile: 503.342.2668 | Fax: 503.296.5502
519 SW 3rd Ave. Suite 600  Portland, OR 97204

Increase registrations, engage users, and grow your brand with RPX.  Learn more 
at www.rpxnow.com <http://www.rpxnow.com/>


From: [email protected] 
[mailto:[email protected]] On Behalf Of Allen Tom
Sent: Friday, January 22, 2010 10:43 AM
To: Andrew Arnott; John Bradley; Breno de Medeiros; specs
Subject: Re: Problem with nonces and HTTP GET

The SSL security warning is a really terrible UX, and I agree that it doesn't 
make sense to warn on POST but not on GET.

Yahoo is running into the 2KB limit (and the associated SSL warning) with 
alarming frequency and it's really hurting OpenID relative to the proprietary 
SSO solutions.

For a real live example of how the giant AX names are hurting OpenID, see 
http://www.huffingtonpost.com - click on the Login link, then the "Connect with 
Yahoo" button. This kicks off the Hybrid OpenID+Oauth+AX flow which requires a 
POST response - forcing the user to click through a security warning to 
complete the sign in flow. The non-OpenID SSO choices (Facebook/Twitter/GFC) do 
not have this issue.

With regards to changing browsers to not display SSL warnings for POST, or 
relying on smart OpenID clients - we really need a solution right now, since 
the proprietary alternatives are rapidly being adopted.

WRT the nonce - I think it would make more sense for RPs to just check the 
timestamp, and allow replay for a "narrow" window, like 10 minutes. There are 
many legitimate reasons why a request could be replayed - intermediate proxy 
servers might do weird things, the user might hit reload/back/forward etc.

Allen


On 1/22/10 10:06 AM, "Andrew Arnott" <[email protected]> wrote:
Ideally we could use POST, but avoid the browser warning that information is 
crossing the SSL world into the non-SSL world.  This might be arguable anyway 
since sending information can be done with GET or POST, so why warn for POST 
and not for GET?  If we can get browsers to not warn for POST we're gold.

Alternatively, and perhaps more likely, if we're moving in the direction of 
smart client browser (plugins), and these have been shown to benefit from 
extensions to the OpenID spec, perhaps we can leverage these to always use POST 
without displaying the warning to the user somehow.
--
Andrew Arnott
"I [may] not agree with what you have to say, but I'll defend to the death your 
right to say it." - S. G. Tallentyre


On Fri, Jan 22, 2010 at 9:14 AM, John Bradley <[email protected]> wrote:
The big problem with POST is RP's that use non-ssl endpoints.

One possibility is that the IdP could look at the return_to and discover if it 
is safe to use POST.

In SAML SSO POST is the most common way to return the token.

The other option is artifact binding.  That way the nonce is not in the GET,  
though you probably wind up with the same effect if the RP tries to resolve the 
artifact more than once.

John B.
On 2010-01-22, at 12:39 PM, Andrew Arnott wrote:
HTTP GET is supposed to be completely effect-free on the server.  But nonces in 
OpenID messages violate that aspect of the HTTP spec, since any subsequent GET 
with the same positive assertion will (or should) fail.  I speculate that some 
random login failures on StackOverflow 
<http://meta.stackoverflow.com/questions/32247/cant-login-to-so-with-openid-the-signature-verification-failed/36583#36583>
  may be caused because a browser, an accelerator plugin, or a proxy attempted 
to repeat the assertion-carrying GET request (since that's supposed to be 
safe), and a subsequent request is the one whose response is displayed in the 
browser, failing user login.
 
<http://meta.stackoverflow.com/questions/32247/cant-login-to-so-with-openid-the-signature-verification-failed/36583#36583>
POST is a better fit with the HTTP spec for how the message is actually 
processed on the server.  I know lately we've been looking for ways to cram 
more data into < 2KB payloads so we can get off POST and onto GET since the 
user experience is better.  But I wonder if we can put our heads together and 
figure out how to have our cake and eat it too with this nonce problem.  This 
error doesn't come up often, but it can come up, apparently does come up, and 
is a natural side-effect of the way OpenID communicates.

Any ideas?

--
Andrew Arnott
"I [may] not agree with what you have to say, but I'll defend to the death your 
right to say it." - S. G. Tallentyre
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