Should we recommend that return_to url is always HTTPS? What about realm?
George Fletcher
gffletch at aol.com
Thu May 14 18:45:36 UTC 2009
OK, thanks. I think I understand how you are relating realm to PPID. I
agree that we probably have to generate the PPIDs on the user:realm pair
(note, it would be very nice if realm were included in the association
request; but that's a different discussion). Even this causes some
problems if a set of RPs share the same realm... but it's the best that
can be done right now with the current spec.
While realm normalization isn't required for PPIDs to work and be
unique, practically we'll have to do something so that users have a
least a chance of a consistent experience. Note that this will pretty
much require an RP to never change their realm because if they do, all
the PPIDs will regenerate and the user's data will be lost.
Thanks,
George
John Bradley wrote:
> George,
>
> By PPID I am referring to a pairwise pseudonymous identifier like PPID
> in info-card or the IDs Google uses.
>
> The 2.0 spec talks about "OP identifiers" being used to allow the user
> to select an identity at the OP. (badly and in a confusing way)
>
> No place in 2.0 talks about pseudonymous identifiers of any sort.
> So the question is if the user doesn't want there activity
> correlated, or a RP for PII legal reasons doesn't want a correlatable
> identifier for the user how should the OP produce such an identifier.
>
> Further if that type of identifier is required by the RP how would
> they indicate that.
>
> The realm would only be used by the OP to produce the "private
> personal identifier".
>
> Doing this raises additional questions about how to normalize the Realm.
> Do you want to produce the same PPID for all of these?
>
> http://example.com
> http://www.example.com
> https://www.example.com
> http://www.example.com:80
> http://www.example.com:443
> https://www.example.com:443
> http://www.example.com/
>
> The RP might so to make it at least predictable there should be some
> normalization rule.
>
> I am sure Breno will jump in I know this is one of his issues.
>
> So while all openIDs are on some sense pseudonymous, I was referring
> to the pairwise ones.
>
> Regards
> John B.
>
> On 14-May-09, at 1:17 PM, George Fletcher wrote:
>
>> John,
>>
>> By PPID do you mean the InfoCard unique User:RP identifier? Or are
>> you referring to the use of pseudonymous identifiers within OpenID?
>>
>> If the latter, I didn't see the thread that was suggesting that the
>> pseudonymous identifiers match the realm. I would be against that
>> suggestion. The spec requires the RP to do discovery on the
>> pseudonymous identifier to prove that the OP that returned the
>> response is authoritative for the pseudonymous identifier. With this
>> mechanism, the realm should not need to match the identifier.
>>
>> Thanks,
>> George
>>
>> John Bradley wrote:
>>> Luke,
>>>
>>> From a URI point of view the two URI are different and it can't be
>>> considered steeping up security.
>>>
>>> I understand that is what would normally happen but it violates some
>>> basic principals.
>>>
>>> It also compromises RP discovery.
>>> A wijldcard in the realm may be the better solution. Though you may
>>> not want to include matching all protocols.
>>>
>>> In the other thread we are discussing PPID like identifiers. If
>>> they are based on the realm as people are discussing, introducing
>>> wildcards etc introduces the question of realm normalization on that
>>> side.
>>>
>>> John Bradley
>>>
>>>
>>> On 14-May-09, at 11:25 AM, Luke Shepard wrote:
>>>
>>>> So, RP delegation sounds like a very general solution to the
>>>> problem, and seems okay to push for. But I think there’s a much
>>>> simpler solution that solves the specific problem I described below:
>>>>
>>>> RULE:
>>>> If the realm is http, then the return_to can be either http or https.
>>>>
>>>> So this would be legal:
>>>>
>>>> realm: *http*://open.lukeshepard.com/
>>>> return_to: *https*://open.lukeshepard.com/openid/receiver.php
>>>>
>>>> This would NOT be legal – you can’t go the other way.
>>>>
>>>> realm: *https*://open.lukeshepard.com/
>>>> return_to: *http*://open.lukeshepard.com/openid/receiver.php
>>>>
>>>> So, the receiver should be allowed to INCREASE its security level
>>>> from the realm, but not decrease.
>>>>
>>>> This is analogous to wildcards for the protocol instead of just
>>>> subdomain. Another alternative would be to have explicit wildcards
>>>> for the protocol, or to allow realms with relative protocols, like:
>>>>
>>>> explicit wildcard: *://open.lukeshepard.com
>>>> relative protocol: //open.lukeshepard.com
>>>>
>>>>
>>>>
>>>> On 5/14/09 7:19 AM, "John Bradley" <jbradley at mac.com> wrote:
>>>>
>>>> I agree that RP delegation should be possible and even desirable.
>>>>
>>>> To do that safely the OP needs to do RP discovery over SSL or
>>>> discover a XRD with detached sig for the RP.
>>>>
>>>> Otherwise you open up Man in the Middle attacks.
>>>> My point was that in the existing spec to prevent interception of
>>>> tokens and attributes, the Realm that is displayed by the OP to
>>>> the user needs to match where the assertion is sent.
>>>>
>>>> I agree that this is something that should be addressed in openID
>>>> 2.1 ether for XRD with dsig or via XRDS with TLS.
>>>>
>>>> John B.
>>>>
>>>> On 14-May-09, at 12:24 AM, Dirk Balfanz wrote:
>>>>
>>>> I don't see why a realm shouldn't be able to delegate to a
>>>> return_to URL the same way that a user id can delegate to an
>>>> OP endpoint. This includes delegating from http to https, or
>>>> even to a different domain altogether. Over on the XRI TC
>>>> we've been talking about how to do this securely, e.g., by
>>>> signing the XRD that does the delegation:
>>>> http://wiki.oasis-open.org/xri/XrdOne/XmlDsigProfile
>>>> Dirk.
>>>>
>>>> On Wed, May 13, 2009 at 7:43 PM, John Bradley
>>>> <jbradley at mac.com> wrote:
>>>> > Luke,
>>>> > Realm was called trust_root in 1.1, and is a bit like
>>>> audience restriction
>>>> > in SAML.
>>>> > It is the display version of the return_to, and also used
>>>> for RP discovery
>>>> > by the OP.
>>>> > I am not certain what the problem is with it being https: if
>>>> the return_to
>>>> > is https:.
>>>> > There is explicitly no connection to be inferred by DNS
>>>> authority between
>>>> > URI differing in scheme. > Differentiating TLS
>>>> by its own scheme is a decision we have
>>>> to live with.
>>>> > The user should consent to authentication for the site they
>>>> are logging
>>>> > into.
>>>> > http://open.lukesheppard.com and
>>>> https://open.lukesheppard.com could
>>>> > be different sites.
>>>> > If the RP has both HTTP and HTTPS the best practice would be
>>>> to always use
>>>> > the https: version for realm so that RP discovery cant be
>>>> spoofed via DNS.
>>>> > Regards
>>>> > John B.
>>>> > On 13-May-09, at 2:10 AM, specs-request at openid.net wrote:
>>>> >
>>>> > Date: Tue, 12 May 2009 23:10:38 -0700
>>>> > From: Luke Shepard <lshepard at facebook.com>
>>>> > Subject: Should we recommend that return_to url is always
>>>> HTTPS? What
>>>> > about realm?
>>>> > To: OpenID Specs Mailing List <specs at openid.net>
>>>> > Message-ID: <C62FB26E.BCE7%lshepard at facebook.com
>>>> <mailto:C62FB26E.BCE7%25lshepard at facebook.com> >
>>>> > Content-Type: multipart/related;
>>>> > boundary="_004_C62FB26EBCE7lshepardfacebookcom_";
>>>> > type="multipart/alternative"
>>>> >
>>>> > --_004_C62FB26EBCE7lshepardfacebookcom_
>>>> > Content-Type: multipart/alternative;
>>>> > boundary="_000_C62FB26EBCE7lshepardfacebookcom_"
>>>> >
>>>> > --_000_C62FB26EBCE7lshepardfacebookcom_
>>>> > Content-Type: text/plain; charset="iso-8859-1"
>>>> > Content-Transfer-Encoding: quoted-printable
>>>> >
>>>> > In testing my relying party, it seems clear that the
>>>> return_to url SHOULD a=
>>>> > lways be HTTPS. Therefore, then, the realm will always need
>>>> to be HTTPS as =
>>>> > well.
>>>> >
>>>> > If the return_to is HTTP, then if the response comes in the
>>>> form of a POST =
>>>> > from a provider that supports SSL, then the user will see
>>>> a browser warning=
>>>> > for posting to an insecure form.
>>>> >
>>>> > Here's an example:
>>>> >
>>>> > - realm: http://open.lukeshepard.com/
>>>> > - return_to: http://open.lukeshepard.com/openid/receiver.php
>>>> > - provider endpoint: https://www.google.com/accounts/o8/ud
>>>> >
>>>> > Let's suppose that the response is too long for a GET
>>>> redirect, so the prov=
>>>> > ider chooses to POST (as Google and others sometimes do).
>>>> >
>>>> > The user would see a warning like this:
>>>> >
>>>> > [cid:3325014638_6495490]
>>>> >
>>>> > To preserve the user experience and avoid that popup,
>>>> relying parties would=
>>>> > want to make sure their receiver is HTTPS.
>>>> >
>>>> > Alternative
>>>> >
>>>> > What do you think about loosening the realm/return_to
>>>> protocol/domain match=
>>>> > requirements?
>>>> >
>>>> > This kinda sucks though, since it means the REALM also must
>>>> be HTTPS, even =
>>>> > though the HTTP version would seem to be "canonical". I
>>>> wonder, would we al=
>>>> > low an HTTPS return_to if the realm was HTTP? It seems that
>>>> the HTTP versio=
>>>> > n of the realm would be better, and should be able to mean
>>>> "accept either p=
>>>> > rotocol". Or better yet, you should be able to specify a
>>>> realm without a pr=
>>>> > otocol at all.
>>>> >
>>>> > Thoughts?
>>>> >
>>>> > _______________________________________________
>>>> > specs mailing list
>>>> > specs at openid.net
>>>> > http://openid.net/mailman/listinfo/specs
>>>> >
>>>> >
>>>>
>>>>
>>>>
>>>
>>> =
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