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Re: Question

2001-03-22 22:26:12
And this is one way in which MIME was broken to begin with, because
it didn't play nice with security.  With security multiparts, you
MUST NOT change the message in transit.  If you want to change it,
you must super-encode it, so that in the end you can return to the
original bit-stream of the original message.

-derek

Taral <taral(_at_)taral(_dot_)net> writes:

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On Thu, Mar 22, 2001 at 10:59:16PM -0500, Derek Atkins wrote:
The multipart/security RFC (please excuse me for not spewing the
number) specifically forbids MIME agents from re-calcuating the
_INTERNAL_ CTE of a message.  You may change the CTE of a message for
transport, but you must revert to the original CTE before security
decapsulation.
=20
In other words, sendmail may apply a radix64 to the message provided
that the receiving sendmail reverts the radix64 back to the original
form.  In other other words, multipart/security forbids the use of
this MIME feature.

This seems awfully strange. The whole point of MIME is to be able to
be permissive in these kinds of things. Having read the MIME standards a
few times, I would never have assumed that a multipart type would ever
have special restrictions like this based on subtype. In fact,
multipart/signed is not required to be implemented by agents, and they
are _explicitly_ permitted to treated like multipart/mixed, in which the
CTE can be changed if recoding is needed.

--=20
Taral <taral(_at_)taral(_dot_)net>
Please use PGP/GPG to send me mail.
"Never ascribe to malice what can as easily be put down to stupidity."

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-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
       warlord(_at_)MIT(_dot_)EDU                        PGP key available

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