Subject: [secdir] secdir review of draft-ietf-eai-downgraded-display-02

From: Samuel Weiler <[email-masked]>
Date: Wed, 7 Oct 2009 11:20:00 -0400 (EDT)

I am reviewing this document as part of the security directorate's 
ongoing effort to review all IETF documents being processed by the 
IESG.  These comments were written primarily for the benefit of the 
security area directors.  Document editors and WG chairs should treat 
these comments just like any other last call comments.

I concur with Pasi's already-filed Discuss re: the difficulty of
following Section 4.  I suggest adding a plain-language summary.  If
my understanding is correct, that might be:

Show the MIME-decoded versions of each "address header field" (the
"Downgraded-" versions) if and only if the MUA's own running of the
RFC5504 downgrading algorithm on that "Downgraded-" header matches
(with some canonicalization) the corresponding header field in the
message.  Otherwise, and for all non-address headers, don't change the
headers.

The security considerations section refers to 5504 and 4952.  I
suggest including verbatim some of the warnings from 5504,
particularly the fourth paragraph of 5504's section 7 noting that 
these transformations may break certain message integrity mechanisms.

Editorial:
       "The "Downgraded-" header field and corresponding header field MAY
       NOT HAVE RELATIONS." [emphasis mine] is an awkward turn of phrase.