1. Encrypted/encyphered/whatever-you-call-it chunk: application/pem
This declares the chunk to be opaque to everyone except the pem application.
THere are no rules or restrictions on the nature of the content. Since
MIME can't know what's in there, it's none of MIME's business. If PEM
chooses to put MIME-like stuff in there, then that is fine but invisible
to MIME. After de-cryption, PEM gets to feed it back to a MIME processor,
It's not *quite* this simple. MIME defines a structure the contents (er..
the *representation* anyway) must fit within. So part of MIME's business
is that whatever appears in the chunk not look like a separator line.
Your second proposal should be fleshed out a bit. I'm afraid I don't
quite catch your drift on it ...