Re: [jose] Header criticality -- hidden consensus?

Vladimir,

It is useful to see actual APIs and code trying to implement this MUST-understand-everything rule.

I can't quite see how your API allows a caller to indicate that is understands a new header parameter. Your HeaderFilter lets the caller *see* which field names the library "understands". JWSHeaderFilter goes further and allows the caller to *set* the accepted algorithms. I couldn't find, say, setAcceptedParameters(...).

Perhaps you are supposed to extend, say, MACVerifier with your own class that lists an extra field?

--
James Manger

> -----Original Message-----
> From: jose-bounces@ietf.org [mailto:jose-bounces@ietf.org] On Behalf Of
> Vladimir Dzhuvinov / NimbusDS
> Sent: Saturday, 9 February 2013 5:35 PM
> To: Richard Barnes; jose@ietf.org
> Subject: Re: [jose] Header criticality -- hidden consensus?
> 
> Hi Richard,
> 
> I understand your concern. With some bit of interface engineering we
> managed to have this requirement covered at library level, by allowing
> client apps to specify additional accepted parameters. If the JOSE
> library encounters a header with an unexpected name, it will mark the
> message as bad on the spot, so it won't be passed on to the app code at
> all.
> 
> You can take a look at the interface Javadocs here:
> 
> http://nimbusds.com/files/jose-
> jwt/javadoc/com/nimbusds/jose/HeaderFilter.html
> 
> And the actual code at the Git repo:
> 
> https://bitbucket.org/nimbusds/nimbus-jose-
> jwt/src/bef49c225aae194b6c40a376aee36b9af37a5da6/src/main/java/com/nimb
> usds/jose/HeaderFilter.java?at=master
> 
> 
> 
> What's more, this interface allows even certain standard headers from
> the JWS/JWE spec to not be denied (say if the client app doesn't want
> to
> accept X509 cert URLs, etc).
> 
> 
> I hope this helps,
> 
> Vladimir
> 
> 
> --
> Vladimir Dzhuvinov : www.NimbusDS.com : vladimir@nimbusds.com
> 
> 
> 
> 
> -------- Original Message --------
> Subject: [jose] Header criticality -- hidden consensus?
> From: Richard Barnes <rlb@ipv.sx>
> Date: Fri, February 08, 2013 11:11 pm
> To: "jose@ietf.org" <jose@ietf.org>
> 
> We're 24 votes into the header criticality poll, so I thought I would
> go
> ahead and take a look at how the results are shaping up.  My initial
> tabulation is below.  The result on the FIRST POLL (the main one) is as
> follows:
> 
> No: 10
> Yes: 14
> 
> 
> What I find striking, however, is that every single person that voted
> "Yes" on the FIRST POLL also voted "Yes" on the SECOND POLL.  So nobody
> who thinks that all headers should be critical thinks that a JOSE
> library should actually be required to enforce this constraint.  And
> that means that enforcing that all headers are supported cannot be a
> MUST according to RFC 2119.
> 
> 
> So I wonder if there's consensus to remove the following text from JWE
> and JWS:
> -----BEGIN-JWE-----
>    4.   The resulting JWE Header MUST be validated to only include
>         parameters and values whose syntax and semantics are both
>         understood and supported.
> 
> -----END-JWE-----
> -----BEGIN-JWS-----
>    4.  The resulting JWS Header MUST be validated to only include
>        parameters and values whose syntax and semantics are both
>        understood and supported.
> 
> -----END-JWS-----
> 
> 
> Otherewise, a JOSE library conforming to these specifications would be
> REQUIRED (a synonym to MUST in 2119) to reject a JWE/JWS that contains
> an unknown header, contradicting all those "Yes" votes on the SECOND
> POLL.
> 
> 
> --Richard
> 
> 
> 
> 
> 
> 
> -----BEGIN-Tabulation-----
> 1       2       3    Name:
> N       -       -    Bradley
> N       -       -    Ito
> N       N       A    Yee
> N       N       B    Barnes
> N       N       B    Rescorla
> N       N       C    Manger
> N       N       C    Octman
> N       Y       A    Fletcher
> N       Y       A    Miller
> N       Y       A    Sakimura
> Y       Y       -    D'Agostino
> Y       Y       A    Biering
> Y       Y       A    Brault
> Y       Y       A    Hedberg
> Y       Y       A    Jay
> Y       Y       A    Jones
> Y       Y       A    Marais
> Y       Y       A    Nadalin
> Y       Y       A    Nara
> Y       Y       A    Nennker
> Y       Y       A    Solberg
> Y       Y       B    Hardt
> Y       Y       B    Medeiros
> Y       Y       C    Matake
> Y       Y       C    Mishra
> 
> -----END-Tabulation-----
> 
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