The PGP/MIME vs inline discussion seems to be on an up-cycle, and it
showed up on both the PGP and GnuPG mailing lists in the past week.
I don't mean to revisit the debate itself, so suffice to say that some
people use it, some people don't use it, some people can't use it, and
there are difficulties when a user sends PGP/MIME to someone who can't
handle it.
Given all that, would there be some benefit in a standard way for a
user to advertise that he can handle PGP/MIME? Specifically, a
"features" subpacket bit to say "I can handle PGP/MIME".
It's important not to read too much into such a feature bit. Having
the bit set does not mean that PGP/MIME must be used, and having the
bit unset does not mean that PGP/MIME must not be used. A PGP/MIME
bit, rather like the MDC bit, simply means that the user is capable of
handling a PGP/MIME message. How a sender handles that extra
information is up to him. Senders remain free to use configuration,
heuristics, guessing, or whatever methods they like to decide when to
use PGP/MIME.
To be sure, this is a little odd since OpenPGP/MIME and OpenPGP are
two different things, and 2440bis is not the OpenPGP/MIME spec.
Nevertheless, since you can't do OpenPGP/MIME without OpenPGP, it
would be convenient to be able to advertise this capability via
OpenPGP.
Proposed text:
In section 5.2.3.24, add:
0x02 - Recipient is capable of handling OpenPGP/MIME (RFC-3156).
In the same section, change this sentence:
In the case of Modification Detection, an implementation may
freely infer this feature from other suitable
implementation-dependent mechanisms.
to:
In the case of Modification Detection and OpenPGP/MIME, an
implementation may freely infer this feature from other suitable
implementation-dependent mechanisms.
David