Subject: Re: [ietf-dkim] Fwd: [Lurk] Another outside the "box" use case: DKIM

From: Dave Crocker <[email-masked]>
Date: Thu, 21 Apr 2016 07:23:37 -0700

On 3/2/2016 1:35 AM, Stephen Farrell wrote:
> LURK is an IETF mailing list that's discussing developing a
> solution to the "offload TLS without giving the CDN my private
> key" problem.

The premise seems to be that there is a single private key.

DKIM permits an arbitrary of private keys to be associated with the 
domain name.  So assigning one solely for use by a third-party -- and 
deciding when to terminate it -- is convenient and carries no effect on 
other uses.

d/

-- 

   Dave Crocker
   Brandenburg InternetWorking
   bbiw.net
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From: Dave Crocker <[email-masked]>
Date: Thu, 21 Apr 2016 10:36:10 -0700

On 4/21/2016 10:30 AM, Jon Callas wrote:
> Most of all, we planned for similar uses. Not CDNs in particular, but the reason DKIM talks about the "administrative domain" (Dave's term) is because we knew that CDNs and other people (heck, like outsourced email senders) would need to be able to have the ability to do whatever.

Completely ancillary notational trivia:

    The term 'administrative domain' is in the Email Architecture spec, 
RFC 5598.  I used it there, with some irony, after its previous use for 
the OSI/CCITT X.400 specifications.

They used the term (Administrative management domain) to refer to the 
public carriers, as distinct from the local enterprises.  In the 
Internet's architecture, such distinctions are operational, not 
architectural.  Architecturally, all domains are equal...

d/

-- 

   Dave Crocker

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From: Jon Callas <[email-masked]>
Date: Thu, 21 Apr 2016 10:30:33 -0700

> On Apr 21, 2016, at 7:23 AM, Dave Crocker <[email-masked]> wrote:
> 

I concur. All you have to do with DKIM is to make sure that the key associated with a given message is available, and having that be non-uniform is a feature of the base protocol. The private key is owned by the sending machinery -- potentially an edge MTA -- only. The cost of destroying a key (remember, they're keys, not certs) is only that the messages presently in-flight might not verify. 

	Jon