Hi Jim,
Please see my replies to Robert and Richard. I believe they cover the point
you're making below.
-- Mike
-----Original Message-----
From: Jim Schaad [mailto:ietf(_at_)augustcellars(_dot_)com]
Sent: Monday, December 14, 2015 10:42 PM
To: Mike Jones <Michael(_dot_)Jones(_at_)microsoft(_dot_)com>; 'Robert Sparks'
<rjsparks(_at_)nostrum(_dot_)com>; 'General Area Review Team'
<gen-art(_at_)ietf(_dot_)org>; ietf(_at_)ietf(_dot_)org;
jose(_at_)ietf(_dot_)org;
draft-ietf-jose-jws-signing-input-options(_at_)ietf(_dot_)org
Subject: RE: [jose] Gen-Art LC review:
draft-ietf-jose-jws-signing-input-options-06
Mike,
This is interesting from a couple of points.
Why would you have an application that uses "b64":false as a parameter.
This is longer and thus would appear to be undesirable from that perspective.
It might imply that the application is using both true and false for b64, but
that is something that you have said is not recommended.
It would, of course, be perfectly acceptable to say that crit needs to be
present only if b64 is true. This would address your worry about it failing
for the case of b64:false being included.
Jim
-----Original Message-----
From: jose [mailto:jose-bounces(_at_)ietf(_dot_)org] On Behalf Of Mike Jones
Sent: Sunday, December 13, 2015 8:05 PM
To: Robert Sparks <rjsparks(_at_)nostrum(_dot_)com>; General Area Review Team
<gen- art(_at_)ietf(_dot_)org>; ietf(_at_)ietf(_dot_)org;
jose(_at_)ietf(_dot_)org;
draft-ietf-jose-jws-signing-input-
options(_at_)ietf(_dot_)org
Subject: Re: [jose] Gen-Art LC review:
draft-ietf-jose-jws-signing-input-options-
06
Hi Robert,
You asked "_WHY_ is crit not sufficient? I think that's the thing
that's
missing as
motivation."
There are two goals we're discussing, which are related:
(a) Having an application that uses "b64":false work.
(b) Having an application that receives a JWT with "b64":false not
misinterpret
the payload content.
Including "crit":["b64"] would be sufficient to achieve (b), as it
would
cause the
JWS to be rejected by implementations not supporting "b64". But it
does
not
achieve (a), since the JWS would be rejected.
In contrast, using an implementation that understands "b64" achieves
both
(a)
and (b) without needing to include "crit". That's why it's not required.
Does that make sense now?
Best wishes,
-- Mike
-----Original Message-----
From: Robert Sparks [mailto:rjsparks(_at_)nostrum(_dot_)com]
Sent: Sunday, December 13, 2015 1:11 PM
To: Mike Jones <Michael(_dot_)Jones(_at_)microsoft(_dot_)com>; General Area
Review Team
<gen-art(_at_)ietf(_dot_)org>; ietf(_at_)ietf(_dot_)org;
jose(_at_)ietf(_dot_)org;
draft-ietf-jose-jws-signing-
input-options(_at_)ietf(_dot_)org
Subject: Re: Gen-Art LC review:
draft-ietf-jose-jws-signing-input-options-06
Cutting away a bit to focus on the question:
On 12/12/15 8:32 PM, Mike Jones wrote:
Hi Robert. Thanks for the useful review. Replies are inline below...
-----Original Message-----
<snip/>
I would have been much more comfortable with a consensus to require
'crit'.
(Count me in the rough if this proceeds with crit being optional).
I assume there is a strong reason to allow for option 1. Please add
the motivation for it to the draft, and consider adding a SHOULD
use
'crit'
requirement if option 1 remains.
It's a reasonable request to have the draft say why "crit" isn't
required. My
working draft adds the following new paragraph at the end of the
security considerations section to do this. Unless I hear objections,
I'll plan on
publishing
an updated draft with the paragraph shortly.
"Note that methods 2 and 3 are sufficient to cause JWSs using this
extension
to be rejected by implementations not supporting this extension but
they
are not
sufficient to enable JWSs using this extension to be successfully used
by applications.
The conclusion you draw here is not at all obvious.
_WHY_ is crit not sufficient? I think that's the thing that's missing
as
motivation.
Thus, method 1 - requiring support for this extension - is the
preferred
approach and the only means for this extension to be practically
useful to applications. Method 2 - requiring the use of <spanx
style="verb">crit</spanx> -
while theoretically useful to ensure that confusion between encoded
and unencoded payloads cannot occur, is not particularly useful in
practice,
since
method 1 is still required for the extension to be usable. When method
1
is
employed, method 2 doesn't add any value and since it increases the
size
of the
JWS, its use is not required by this specification."
Nits/editorial comments:
In the security considerations, the last sentence of the first
paragraph needs to be simplified. I suggest replacing it with:
"It then becomes the responsibility of the application to ensure
that payloads only contain characters that will not cause parsing
problems for the serialization used, as described in Section 5. The
application also incurs the responsibility to ensure that the
payload will not be modified during retransmission.
I have simplified this in the manner that you suggested.
Thanks again,
-- Mike
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