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Re: [ietf-dkim] ISSUE: 4871bis-02 - Section 8.14 comments

2010-10-15 08:09:06
On Wed, 13 Oct 2010 18:13:43 +0100, Jim Fenton <fenton(_at_)cisco(_dot_)com> 
wrote:

My inclination is that the spec should say something like:

- The verifier SHOULD consider the signature invalid if a signed header
field occurs an inappropriate number of times in the message header
according to section 3.6 of RFC 5322.
- The verifier MAY consider the signature invalid if it detects other
message syntax violations of RFC 5322.
- (??) The verifier SHOULD consider the signature invalid if the List-Id
header field is signed and occurs more than once in violation of RFC  
2919.

I think the first SHOULD needs to be a MUST (especially as it is a fairly
simple test to implement).

The MAY is fine.

The second SHOULD is fine, except that it should be a blanket coverage of
all other standards that define header fields limited to one occurrence.
We can't expect implementers to keep up-to-date with EVERY such standard,
but they should try to do as much as they can. If SHOULD is too strong for
that sort of approach, then I would make it a MAY with an "encouragement"
do you as much as they can. Obvious candidates are the List-* headers and
RFC204[56].

The last provision worries me a bit because it opens the door to other
specifications that define header fields. On the other hand, I can
picture an attack involving insertion of a bogus List-Id header field in
order to influence the handling of the message.

See above.



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Charles H. Lindsey ---------At Home, doing my own thing------------------------
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