Dear Authors:
The ID defines two MIME content types: multipart/signed and
multipart/encrypted. At this time, I do not wish to make any comments
about the definition of these content types, rather I wish to comment on
the lack of any statement about the relationship of these two content
types.
I assume that a MIME message body can be both signed and encrypted by
applying both multipart/signed and multipart/encrypted. First, I think
that this should be stated explicitly. Second, the order of the
encapsulation is very important. In general, the didital signature should
be applied before encryption. If the message is signed before it is
encrypted, then the signed MIME message body can be forwarded to another
recipient. However, if the the message is encrypted before it is signed,
then forwarding signed MIME message body to another recipient is not
sufficient for that user to process the message; the user should not have
the keys to decrypt the signed ciphertext.
While there might be some esoteric cases where the ciphertext MIME message
body should be signed, I do ot believe that this is the normal case. I
suggest that a section be added to the ID which details this relationship.
Russ