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Dave Crocker <dhc(_at_)dcrocker(_dot_)net> wrote:
Why should more than one signature be allowed?
Let's say I post to a mailing list, and I digitally sign my
message to confirm that the message truly represents my
views, i.e. it was not an unauthorized statement made by
someone else in my name. For this kind of signature it is
good enough to sign the message body, and this is actually
a solved problem. As long as the mailsig mechanism is able
to tranparently handle messages which contain this kind of
signature, I feel that mailsig does not need to address
this particular can of worms.
The mailing list adds a signature to the message which
indicates that it's a legitimate message of that mailing
list, so people who want to receive all messages from
that mailing list can configure their spam filters to
let throse messages through. The mechanism for this kind
of signatures is what I'd like mailsig to specify, and as
far as I can see there is no need for more than one
signature of this type.
What i am asking is the higher-level purpose of the signature.
some examples might be:
1. the signature specifies who will pay for monetary damages caused
by the message
2. the signature specifies who is asserting that the message is
3. the signature specifies that the message is not spam
4. the signature specifies who to contact if there is a problem
My main interest in mailsig is #3.
For this purpose it's important for the signature to cover not
only the body of the message but also all message headers which
are supposed to be displayed or otherwise acted upon by MUAs.
The order of the headers does not matter; sorting the headers
alphabetically before signing would be ok.
Mailing list software which munges messages significantly enough
to break the signature (adding a List-Post: header is enough to
break the kind of signature that I have in mind) should remove
any existing signature with "this is not spam" semantics before
the munging, and afterwards add its own "this is not spam"
For a bit of context I'd like to point to my EMX ("Escrow Message
eXchange") proposal, which is the one way that I see to truly solve
the problem of spam. The details are in
(The part about the need for digital signatures on SMTP messages
is in section 4.9)
Founder & Steering Committee member of DotGNU, see http://dotgnu.org/
Free Software Business Strategy Guide ---> http://FreeStrategy.info
Norbert Bollow, Weidlistr.18, CH-8624 Gruet (near Zurich, Switzerland)
Tel +41 1 972 20 59 Fax +41 1 972 20 69 http://norbert.ch
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