Re: [ietf-dkim] [dmarc-ietf] a slightly less kludge alternative to draft-kucherawy-dmarc-rcpts

[Michael Storz <[e-mail]>]

Am 2016-11-22 17:14, schrieb John R. Levine:
>>> I'm with Murray -- why is this a problem?  Single recipient has been
>>> the de-facto standard for years, and unless you are extremely
>>> bandwidth constrained, it's faster.
>> 
>> No, it's not faster, see my answer to Murray. It's wasting a lot of 
>> ressources.
> 
> People who've measured say the elapsed time is faster, and the extra
> bytes on the wire don't matter.  This is an old argument, and not one
> you're going to win.

Could it be, that we are talking about different things? I have no idea 
what these people measured. I can only talk for my site. Splitting all 
my internal traffic into single-recipient emails would mean an increase 
of 55%. If our mail servers would receive only single-recipient emails 
from the internet the traffic would increase by 13%. The processing of 
an email generates directly real cost in form of electricity and cooling 
etc. which has to be payed with real money. Processing all these 
additional traffic will give me no advantage but cost me real money. We 
try to avoid wasting ressources, Green IT is an important thing at our 
site, see http://www.lrz.de/wir/green-it_en/

> 
>> John, did you read my email? The whole text is about how the leakage 
>> of the BCCs can be prevented and the feature of a multi-recipient 
>> email be preserved. If you see an error in the algorithm, please 
>> explain.
> 
> See previous messages, particularly the ones from Ned Freed.  Any sort
> of multi-recipient signing is subject to guessing attacks.

Since this approach uses Neds alternative 0) b) for the BCC recipients 
no information about BCCs is leaked. This is the part where 
single-recipient emails are needed. But all other recipients can be put 
together into one email because their addresses are already recorded in 
the various header fields.

> 
> This isn't saying that signing the recipient is a good idea, but
> signing them individually is no worse than signing them together and
> avoids the leakage.
> 
> Regards,
> John Levine, [e-mail], Primary Perpetrator of "The Internet for 
> Dummies",
> Please consider the environment before reading this e-mail. 
> https://jl.ly

Michael
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