On Fri, Jan 15, 2010 at 10:41 AM, Richard L. Barnes <[email protected]> wrote:

> I would think not; it's a matter of the client's policy what signatures it
> will issue, and the server's policy which it will accept.
>

That doesn't answer the interop question, though, which is the interesting
one from the standpoint of the spec.  If there is no requirement for a
common minimal-subset then there is no guarantee of interop between a random
client and a random server that both speak the same data protocol.  Most use
cases of OAuth have a custom client for every data API so this isn't an
issue, but that's not necessarily the case, especially as new protocols
start to depend on OAuth for their security needs.


>
> And in any case, OAuth doesn't have any in-band security negotiation, so
> there's no way for the server to ask for a given set of features (e.g.,
> bearer tokens and no TLS) within the protocol.
>
>
See however https://groups.google.com/group/oauth-key-discovery for a very
needed extension that does add key discovery and rotation.  Even without
that, the question is just punted to the out of band documentation:  Is a
server allowed to support only bearer tokens and no TLS for some use case?



--Richard
>
>
>
>
> On Jan 15, 2010, at 1:29 PM, John Panzer wrote:
>
> I think the question at hand is:  If a server says it wants to do bearer
> tokens and no TLS, is a client obligated to interop in order to claim spec
> compliance?
>
> --
> John Panzer / Google
> [email protected] / abstractioneer.org / @jpanzer
>
>
>
> On Fri, Jan 15, 2010 at 10:01 AM, Hurliman, John 
> <[email protected]>wrote:
>
>> +1 to this as well. Any implementation is free to deviate from the spec,
>> at the risk of breaking interoperability.
>>
>> John
>>
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]] On Behalf Of
>> John Panzer
>> Sent: Friday, January 15, 2010 8:43 AM
>> To: Eve Maler
>> Cc: OAuth WG
>> Subject: Re: [OAUTH-WG] Allowing Secrets in the Clear Over Insecure
>> Channels
>>
>> +1 to MUST implement TLS on both sides.
>>
>> I thought we were only discussing whether the server could decide to
>> skip TLS for a particular use case.  No?
>>
>> On Friday, January 15, 2010, Eve Maler <[email protected]> wrote:
>> > The points about matching security to use case are excellent.  This is
>> why I think we're maybe misinterpreting Eran's argument for MUST.  It's not
>> an argument from security alone ("we must always have highest security all
>> the time"); it's an argument from interoperability of security features at
>> Internet scale ("in the general/at-scale case, we should not accept deployed
>> instances that do not support this important security feature").
>> >
>> > On this basis, it's reasonable to argue for MUST for implementing TLS
>> (with no weasel words about "or equivalent", since this isn't a testable
>> protocol clause), for the broad ecosystem benefits.
>> >
>> >         Eve
>> >
>> > On 15 Jan 2010, at 8:06 AM, John Kemp wrote:
>> >
>> >> On Jan 14, 2010, at 7:39 PM, Richard L. Barnes wrote:
>> >>
>> >>>> As such, I can't see how *not* requiring SSL for unsigned requests
>> >>>> could pass muster at an IETF security review.
>> >>>
>> >>> Speaking as someone who does IETF security reviews ...  :)
>> >>>
>> >>> If I were reviewing a document that defines an optional insecure mode
>> of operation (in this case, operating without TLS), I would be looking for
>> basically two things: (1) A discussion of the risks if the insecure mode is
>> used, and (2) a motivation for why these risks might be acceptable in
>> certain cases.  This is in the spirit of "MUST=SHOULD+exception" -- if it's
>> a SHOULD, you need to explain the exception.  In this case, the risks (1)
>> are pretty obvious: A passive observer can steal your password and use it to
>> authenticate as you.  The motivations (2) are what this thread is about.
>> >>>
>> >>> I would also observe that "MUST use TLS or equivalent" is actually the
>> same as "SHOULD use TLS", since the "or equivalent" isn't really specified.
>> >>
>> >> Right. Which is why I'm currently OK with Eran's text either way as I
>> think it allows bearer tokens with *any* other security protections, unless
>> we specify exactly which security properties should be provided by the
>> channel, vs. via other mechanisms.
>> >>
>> >> SAML's "confirmation method" is sort of the equivalent idea to what
>> we've been talking about here (where the method could be "holder-of-key+a
>> signature algorithm", "bearer" or something else) but we also haven't
>> separated out security properties such as integrity or confidentiality for
>> the purposes of this discussion.
>> >>
>> >>> (This is really obvious when you think about it from the perspective
>> of an implementor: If you're going to cover the "or equivalent" cases, then
>> you have to have be able to operate in non-TLS mode.)  The "or equivalent"
>> cases are the ones where not using TLS might be acceptable, i.e., the ones
>> that should be cited as motivations (2) for allowing the non-secure mode.
>> >>>
>> >>> Taking the SECDIR hat off, it seems to me that there are some
>> motivations appearing in this thread:
>> >>> -- Appropriate key management (frequent key refresh)
>> >>> -- Private trusted networks
>> >>> -- John's observation that "URL+token" == "private URL"
>> >>> So ISTM that "SHOULD use TLS" could be motivated here.
>> >>>
>> >>> (Now, all that said, it probably wouldn't hurt to have TLS as a "MUST
>> implement" so that it's there if people want to use it.)
>> >>
>> >> +1
>> >>
>> >> - johnk
>> >
>> >
>> > Eve Maler
>> > [email protected]
>> > http://www.xmlgrrl.com/blog
>> >
>> > _______________________________________________
>> > OAuth mailing list
>> > [email protected]
>> > https://www.ietf.org/mailman/listinfo/oauth
>> >
>>
>> --
>> --
>> John Panzer / Google
>> [email protected] / abstractioneer.org / @jpanzer
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