[ietf-dkim] Change the SSP o= to use words, break out 3rd party?

[Tony Hansen]

We might want to recognize the three orthogonal axes currently covered
by the policy character: sending mail, signatures, and 3rd party
signing. There is also the meta policy of ^/user, which redirects the
search to a different level.

On the sending mail axis you have the range of values of never and allowed.

On the signature axis you have the range of values of unspecified,
never, optional and always/required.

On the 3rd party signing axis we currently have the range of values of
unspecified, never, and allowed.

The current policy character merges all three axes into a single value.

Of course, some combinations are not allowable (e.g., never send +
anything else), and some are implicit rather than explicit (e.g.,
unspecified).

Throwing ^/user in the column with sending mail, and removing the
combinations I think should probably be disallowed, you have the
following table of possible policies:

	sending mail	signature	3rd party	current
	
1	allowed		unspecified	unspecified	NONE
2	allowed		never		never		
3	allowed		never		allowed
4	allowed		optional	never		?/WEAK
5	allowed		optional	allowed		~/NEUTRAL
6	allowed		always		never		!/EXCLUSIVE
7	allowed		always		allowed		-/STRONG
8	never						./NEVER
9	user						^/USER

#1 is implicit with no policy record.

We could continue to extend the single word names for the different
policy combinations, or we could use a syntax that allowed you to
specify each value separately. A couple possible syntaxes might be

2	-signature,-3ps		signature=never,3ps=never
3	-signature,+3ps		signature=never,3ps=allowed
4	~signature,-3ps		signature=optional,3ps=never
5	~signature,+3ps		signature=optional,3ps=allowed
6	+signature,-3ps		signature=always,3ps=never
7	+signature,+3ps		signature=always,3ps=allowed
8	nomail			nomail
9	user			checkuser

These are some things to think about if we choose to keep SSP.

	Tony Hansen
	tony at att.com

Hector Santos wrote:
> ----- Original Message -----
> From: "wayne" <wayne at schlitt.net>
> To: "IETF DKIM WG" <ietf-dkim at mipassoc.org>
> 
> 
>>Tony Hansen mentioned this in the BoF Jabber session, and it is
>>something that I have long thought also.
>>
>>Would it be better to change the o= values to be words instead of
>>single letters?  I find the letters to not be very mnemonic and I
>>don't think we are that short on space.
> 
> 
> That's a great idea! Talking in symbols is fun, but my APL days is long
> over. :-)
> 
> Do you have any suggestions for terms?  I've seen these floating around for
> the last 3-4 months:
> 
> SSP Policies:
> 
>          NONE (no policy [1])
>     o=?  WEAK (signature optional, no third party, see [2])
>     o=~  NEUTRAL (signature optional, 3rd party allowed)
>     o=-  STRONG  (signature required, 3rd party allowed)
>     o=!  EXCLUSIVE (signature required, no 3rd party)
>     o=.  NEVER  (no mail expected)
>     o=^  USER
> 
> [1} a NONE policy is possible where there is no declaration for a SSP.
> 
> [2] Arvel suggested another policy called WEAK which satisfies a
> signature optional but not allowing 3rd party signers.
> 
> --
> Hector Santos, Santronics Software, Inc.
> http://www.santronics.com
> 
> 
> _______________________________________________
> ietf-dkim mailing list
> http://dkim.org