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

2005-11-08 18:34:58
Frank Ellermann wrote:
Tony Hansen wrote:

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


Nice table, thanks.  Are #2 / #3 the same as "no key" ?
How does a 3rd party detect what it should be, 2 or 3 ?

Hmmm, I see an ambiguity in how I was thinking about the possible
policies. When I wrote #2 and #3 above, I was thinking in my mind that

        #2 says you will never ever get a message with a signature.

        #3 says you will never get a message directly with a signature,
        but you may get one from a 3rd party.

but that's not how the signature axis was defined. So it's probable that
#2 and #3 *should* be collapsed into the single item, as you suggest below:

2 -signature,-3ps         signature=never,3ps=never
3 -signature,+3ps         signature=never,3ps=allowed


If we could get rid of #3 somehow it should be simple,
"never" always terminates a policy:

o mnemonic  mail   signature  3rd party  your 
  NONE      other  n/a        n/a        #1
. NEVER     never  n/a        n/a        #8
^ USER      maybe  other      n/a        #9
            maybe  never      n/a        #2
? WEAK      maybe  maybe      never      #4
~ NEUTRAL   maybe  maybe      maybe      #5
! EXCLUSIVE maybe  always     never      #6
- STRONG    maybe  always     maybe      #7

In the spirit of ".", "!", and "?" maybe your case #2
could use ":".

And the mnemonic would be "NOSIG", eh?

All fodder for thought.

        Tony Hansen
        tony(_at_)att(_dot_)com
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