Thanks for your review, Benoit. Per my reply to Stefan, I've added the new
normative section titled "Using "crit" with "b64"" to specify requirements for
situations in which implementations might not understand one another. As you
can see in draft -08 and my reply to Robert Sparks, "crit" is now required in
all situations in which the participants might not understand one another.
I've also adopted Stefan's recommendation that "b64" not be included with a
value of "true".
Thanks again,
-- Mike
-----Original Message-----
From: Benoit Claise [mailto:[email protected]]
Sent: Wednesday, December 16, 2015 11:11 PM
To: The IESG <[email protected]>
Cc: [email protected]; Mike Jones
<[email protected]>; Jim Schaad <[email protected]>;
[email protected]; [email protected]; [email protected];
[email protected]
Subject: Benoit Claise's No Objection on
draft-ietf-jose-jws-signing-input-options-07: (with COMMENT)
Benoit Claise has entered the following ballot position for
draft-ietf-jose-jws-signing-input-options-07: No Objection
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----------------------------------------------------------------------
COMMENT:
----------------------------------------------------------------------
As mentioned by Stefan in his OPS DIR review:
There are coexistence issues between implementations which understand the
notion of the "b64" parameter (i.e. implementing this RFC) and those who do not
(i.e. all existing JWS implementations).
The issues are discussed in Security Considerations (second para up until the
end). The issues with it are:
* the conclusions are not as satisfactory as they could be.
Interoperability is either
- left as an out-of-band and undescribed mechanism ("make sure that only
supporting implementations talk to each other")
- by explicitly marking support for b64 as critical (IMO the only good
solution)
- modifying the payload so that it contains unparseable characters (which may
or may not be possible for the sender depending on the payload characteristics)
* this is placed in Security Considerations while it has actual operational
impact on every transmitted message: in essence it states:
"Sometimes, sender and recipient may misunderstand each other without
noticing". Example given in the draft where the actual message is "NDA1"
while the recipient thinks it was told "405", without a way to notice.
Even if the misunderstanding is not related to security, it can/will have
significant implications for the application.
I believe this can not be left as-is. Luckily, there seems to be an easy way
out:
"Whenever the 'b64' header exists and is set to false, the 'crit' header MUST
also be present and contain 'b64'."
This, maybe in conjunction with
"When the content is intended to be base64 encoded, the 'b64' header SHOULD NOT
be present."
This would make sure that implementations who know nothing of b64 are left
alone (there is no unknown extension, there is no criticality in any such
extension, and the sender did not intend to make use of the feature => all
good). While at the same time for unencoded payloads making deterministically
clear that unencoded transmission is happening, and is required to be
understood.
This would at the same time make a complex piece of Sec Con go away.
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