Re: [dmarc-ietf] Clarifying the value of arc.closest-fail

Instance number please.  Less calculation.

On Fri, 5 Jan 2018, at 16:18, Murray S. Kucherawy wrote:
> On Wed, Jan 3, 2018 at 6:28 PM, Kurt Andersen (b)
> <kboth@drkurt.com> wrote:>> On Wed, Jan 3, 2018 at 11:20 PM, Bron Gondwana
>> <brong@fastmailteam.com> wrote:>>> __
>>> I assume this was the one that you wanted my clarification on?
>> 
>> 
>> Yes, thanks
>> 
>>  
>>> 
>>> 
>>> But let's rewrite it as oldest-pass, because that's clearer.
>>> Your case:>>> 
>>> 
>>> * ARC 1: cv=none, ams.oldest-pass=0
>>> * ARC 2: cv=pass, ams.oldest-pass=1
>>> * ARC 3: cv=pass, ams.oldest-pass=2
>>> * ARC 4: cv=pass, ams.oldest-pass=3
>>> * final recipient ADMD ARC verifier would find cv=pass and evaluate
>>>   ams.oldest-pass as 4.>>> 
>>> And my case where 2 and 3 didn't change anything:
>>> 
>>> * ARC 1: cv=none, ams.oldest-pass=0
>>> * ARC 2: cv=pass, ams.oldest-pass=1
>>> * ARC 3: cv=pass, ams.oldest-pass=1
>>> * ARC 4: cv=pass, ams.oldest-pass=1
>>> * final recipient ADMD ARC verifier would find cv=pass and evaluate
>>>   ams.oldest-pass as 4.>>> 
>>> From which the final recipient can also see that, if they trust ARC
>>> 4 not to lie, neither ARC 2 or ARC 3 changed anything which was
>>> covered by ARC 1's AMS.>>> 
>>> There is no need to trust either ARC 2 or ARC 3's signatures in my
>>> example, which is the point here.  Even if ARC 2 or ARC 3 are not
>>> yet known or trusted, you can tell that they didn't modify this
>>> particular message.>>> 
>>> 
>>> 
>> 
>> Very helpful - thanks. I think that expressing it in the positive "oldest-
>> pass" form makes the point much clearer. Unless there is an outcry
>> from the rest of the group, I'd like to change to this terminology.> 
> Just to be clear, we're saying "*.oldest-pass" will contain the
> instance number of the most recent AMS that passed?  Or is it the
> distance from the verifier to the most recent passing ADMD?> 
> -MSK
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