The technical feature of this specification is to allow non-security-aware
MIME implementations to handle objects which are signed but not sealed.
That is, cleartext is still accessible.
Thank you for this clear description. I must, however, press this issue.
One of the technical arguments that was presented against the multipart
security specification is that, in fact, non-security-aware MIME
implementations would not correctly handle a multipart message construct
that they had not seen before, effectively rendering the cleartext
inaccessible. So, I think it's fair to ask the larger audience:
Is there a proscribed behaviour for handling a new multipart construct ?
What do current MIME implementations do in this situation ?