Dave Crocker wrote:
Right. The idea, as I put it once, was that "If you break it, you
bought it." Put less colloquially, if a mailing list that knows it's
going to mangle the message receives a DKIM-signed message, it should
this was/is a particularly important view, since it relieves the
signing effort of quite a bit of responsibility that would otherwise
require an impossible effort to withstand arbitrary modification.
a derivative bit that emerged from this was the counter-intuitive
possibility that a mailing list capable of doing dkim signing could
choose not to, for a message that is already signed. that is, it
could knowingly preserve the existing signature.
This relates to one of the motivations for multiple signatures. If you
have a non-mangling mailing list, you might want to preserve the
original signature, because it's still valid and some people might want
to base a decision on that. They (or others) might want to know for
sure that it came from the list, because they want to make sure that
they read all messages on the list. A WG chair might have that concern,
for example.
-Jim
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