FYI, Benoit, "crit" is now required with "b64", as you'd requested.

-----Original Message-----
From: Benoit Claise [mailto:[email protected]] 
Sent: Thursday, December 17, 2015 12:12 AM
To: Mike Jones <[email protected]>; The IESG <[email protected]>
Cc: [email protected]; Jim Schaad 
<[email protected]>; [email protected]; [email protected]; 
[email protected]
Subject: Re: Benoit Claise's No Objection on 
draft-ietf-jose-jws-signing-input-options-07: (with COMMENT)

Thanks Mike.

Regards, Benoit
> 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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>
> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
> for more information about IESG DISCUSS and COMMENT positions.
>
>
> The document, along with other ballot positions, can be found here:
> https://datatracker.ietf.org/doc/draft-ietf-jose-jws-signing-input-options/
>
>
>
> ----------------------------------------------------------------------
> 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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