keyflag subpacket and key expiration subpacket

[David Shaw]

On Fri, Dec 16, 2005 at 12:36:37AM +0100, Christoph Anton Mitterer wrote:
> David Shaw wrote:
> 
> >It's tradition and history.  GnuPG will accept subpackets on either
> >the 0x13 (0x10, 0x11, 0x12) or 0x1F, of course, but only generates the
> >0x13.
> >
> So does this mean if a key would have its key-exp-time/key-flags on an 
> 0x1F that gpg would understand this?

Yes.

> >If we switched over to 0x1F, we'd probably break compatibility
> >with other OpenPGP implementations.
> > 
> >
> Well these applications are not really implementations of OpenPGP. The 
> standard clearly specifies which parts an implementation must not 
> implement. And as far as I can see implementations are allowed to don't 
> implement subpackets (but in that case they must consider these packets 
> if the critical bit is set) but they aren't allowed to recognize 
> subpackets only on specifiv sig-types (expect those where the standard 
> itself allows a subpacket type only on special sig-types).

I don't agree that the standard requires this, but even if it did, the
IETF "be conservative in what you generate, liberal in what you
accept" meta-rule applies.  Where is the benefit in using 0x1F and not
being able to communicate with others?

David