From John's WG minutes:
Paul Hoffman asked if the change in the algorithms would case the
S/MIME version number to change (ex: v3.1). John Pawling made the
point that the CMS ASN.1 syntax is not changing, just the algorithms
used with that syntax. He further stated that the algorithms in an
instance of a CMS object are clearly indicated by OIDs populated in
that object, so a version number change is not required. Russ agreed
and made the point that the RFCs would change, but the S/MIME version
number would still be 3. Nobody disagreed with Russ.
Because this is a combination of message syntax and algorithm use (however
identifcal they might look on the wire, and however clearly the algorithms
being used are identified in that representation), I believe that there
needs to be a unique way to represent this. From a practical standpoint as
an application vendor, I want to say "we support S/MIME v3.1" (specifially
meaning that we do not support in any way the Diffie-Hellman variant used in
S/MIME v3, which is a germane difference between the current "S/MIME v3" as
defined in RFC 2633 and "S/MIME son-of-2633").
Blake
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Blake C. Ramsdell
Tumbleweed Communications
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