1. Although PKCS (as I recall) includes some rudimentary notion of trying to
explain what is meant by a signature, i.e., why the object was signed, PEM
does
not. It also doesn't include a timestamp (trusted or otherwise), an
identification of the machine that was used to apply the signature, or a
number
of other potentially useful facts that could have been included within the
signature block with no additional overhead. That's unfortuantely, IMHO, but
probably not fatal.
2. Both X9 and X12 have worked on trying to supply computer readable codes
that
would attempt to explicate the meaning or intent of a signature. I haven't
reviewed them in depth or recently, but I strongly suspect that they may
satisfy one particular subgroup's interest (e.g., banking) and completely
fail
another (e.g., secure distribution of trusted software.)
I think your points 1 and 2 take us back to a common confusion between
Authentication and Authorization. PEM was only ever intended to perform
Authentication. Authorization is whole nother barrel of monkeys.
I certainly agree with that, and clearly understand the difference.
However, even if my signature only establishes my identity, and not my
credibility
or right to make some statement, in order to truly establish nonrepudiation
and/or
to establish the provenance of a signed document, it would be nice to know these
additional details.
Even if I not signing a formal battle order, it would still be nice to have a
convenient way to distinguish between a first draft and the final version after
all
of the corrections have been made.
My point was that MIME provides a convenient way of attaching the equivalent of
Post-It notes, so that concurrences and nonconcurrences, as well as explanatory
material and backup documentation can all be considered as a package.
Bob
--------------------------------
Robert R. Jueneman
Staff Scientist
Wireless and Secure Systems Laboratory
GTE Laboratories
40 Sylvan Road
Waltham, MA 02254
Internet: Jueneman(_at_)gte(_dot_)com
FAX: 1-617-466-2603
Voice: 1-617-466-282