Marc Mutz <mutz(_at_)kde(_dot_)org> quotes:
While we are on the topic of MIME and encryption -- does anyone know
the history behind S/MIME not using multipart/encrypted of RFC 1847
for encrypted data?
Politics AFAIK. The encryption stuff in RFC 1847 was part of the MOSS
worldview, and MOSS != S/MIME. At the time, RSADSI and the RSA patent were a
bigger hammer, so S/MIME won.
(Having said that, multipart/encrypted is pretty clunky (signed data is a
different issue). OTOH given the perpetual-motion-machine nature of debates
over this in 1995-1996, it's arguable that any decision would have been
regarded as bad by some subset of people).