"typ" is there to dynamically answer the question "What is this data
structure?" for applications. It's needed in cases that that's potentially
ambiguous. If for instance, a token might be either a Facebook signed request
or a JWT, the "typ" value could be used to distinguish between them.
You're wrong that "cty" could be used for that, because "cty" answers the
question "What is the data structure that is the payload of this JOSE message?"
- not "What is this data structure?". The distinction is particularly
important because as of -09 we decided to allow additional header parameters to
be added by applications that must be ignored if not understood. So "cty"
doesn't provide a comprehensive answer to the question "What is this data
structure?".
I know of no OAuth Mechanism for providing a general-case answer to the
question "What is this data structure?" (other than the use of "typ" :)). What
specifically were you thinking of there?
So JWT needs it, and is a valid application. John Bradley has also described a
number of other potential uses. Again, I haven't heard anyone say that Jim's
original logic for why "typ" is the way it is today was wrong - only that more
clarification is needed, which we'll do.
-- Mike
From: [email protected] [mailto:[email protected]] On Behalf Of Richard
Barnes
Sent: Friday, June 07, 2013 7:54 AM
To: Mike Jones
Cc: [email protected]; Dick Hardt
Subject: [jose] Use case for "typ" (Re: What are we doing here?)
[Popping out to a separate thread, since we're into specifics here]
Mike:
I asked earlier for an example of an application that that needs "typ", noting
that JWT doesn't count because it can provide that via two other channels
("cty" and OAuth). Could you provide one?
Thanks,
--Richard
On Fri, Jun 7, 2013 at 10:48 AM, Mike Jones
<[email protected]<mailto:[email protected]>> wrote:
I agree that we should provide some additional clarification on the intended
purpose for the "typ" and "cty" parameters. We just did provide substantial
additional clarification for "crit" in -11, based on the working group
decisions at the interim meeting. Are there other specific things that you'd
suggest that we clarify, Dick?
-- Mike
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]<mailto:[email protected]>] On Behalf Of Dick
Hardt
Sent: Friday, June 07, 2013 7:33 AM
To: Richard Barnes
Cc: Mike Jones; [email protected]<mailto:[email protected]>
Subject: Re: [jose] What are we doing here?
MIke: I don't find your response very useful for understanding the question
Richard proposed. I find the spec confusing as to what I am supposed to do when
as an implementer. It seems that it is clear to all the people associated with
OpenID Connect, but without that context, it is confusing, and frankly, some of
the parameters seem like hacks to me. Perhaps some additional clarification on
what the parameters are intended for would assist?
-- Dick
On Fri, Jun 7, 2013 at 7:23 AM, Richard Barnes
<[email protected]<mailto:[email protected]>> wrote:
Of course, motherhood, apple pie, etc. :)
The question is what we're trying to help developers do. The developers I talk
to want a simple tool to do crypto stuff, full stop. They don't want semantic
validation, critical fields, etc.
The adoption you're pointing to is not really relevant to the process here.
The deployed implementations you're talking about are all in a limited space,
covering one use case. And the current solution comes with baggage for that
use case that adds complexity for everyone else. If you wanted to address that
one use case, you should have chartered for that, not general signing and
encryption.
Nonetheless, on timing, I agree that I'm getting a little bored with fighting
over this :) I'm working on a review of -11 that tries to package up all the
remaining comments such that they can get resolved and we can move on with life.
--Richard
On Fri, Jun 7, 2013 at 1:18 AM, Mike Jones
<[email protected]<mailto:[email protected]>> wrote:
Excellent question, Richard, because it gets to the heart of why the JOSE specs
are already highly successful and widely adopted.
- We are building useful tools that solve real problems for developers.
- We are practically demonstrating the value of rough consensus and running
code.
- We are making simple things simple.
- We are making complex things possible, when necessary (but not at the
expense of keeping simple things simple).
- We are developing specs with an explicit goal of enabling ubiquitous
adoption.
- We are developing specs guided by practical engineering tradeoffs to enable
commonly useful functionality in a straightforward manner.
The level of adoption, with dozens of deployed implementations, is compelling
evidence that we've already achieved the goals above. It's time to "ship it",
as making the JOSE specs actual standards will only increase their adoption and
value to the industry.
That's what we're doing here.
-- Mike
P.S. I would be careful reasoning from the premise of "The perfect protocol is
one from which nothing can be removed". By that logic, the perfect
specification is the null specification, which leaves all possibilities open,
and solves no actual problems. ;-)
From: [email protected]<mailto:[email protected]>
[mailto:[email protected]<mailto:[email protected]>] On Behalf Of
Richard Barnes
Sent: Thursday, June 06, 2013 2:44 PM
To: [email protected]<mailto:[email protected]>
Subject: [jose] What are we doing here?
The conversation about "typ" has brought us back to a familiar question for
this working group -- what are we trying to do here?
The current document is ambiguous on this topic. On the one hand, it mostly
covers the crypto bases, with things like "alg" and "enc". On the other hand,
it mixes in application design concepts like "typ" and "crit". The result is a
spec that's ambiguous in purpose and complex. If I'm building an application
with this, how do I decide what goes in the "crit" field, or what values to use
for "typ"?
The charter for this working group is not ambiguous on this topic. This group
is chartered to do signing and encryption. The JOSE formats should carry the
parameters needed to perform those operations. Anything else is extraneous,
and in the spirit of "The perfect protocol is one from which nothing can be
removed", should be removed.
Now, I'm not going to be a hard-liner on this. I won't complain about "zip"
and "cty", since they are clearly defined and have clear use cases. But "crit"
and "typ" are so ambiguous and so little supported by use cases*, that they
really should go.
</rant>
--Richard
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-- Dick
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