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Re: Feedback on draft-burke-content-signature-00.txt

From: Dave CROCKER <dhc2@dcrocker.net>
Date: Sun, 27 Mar 2011 15:48:44 +0200
Message-ID: <4D8F403C.2050208@dcrocker.net>
To: Bill Burke <bburke@redhat.com>
CC: Eran Hammer-Lahav <eran@hueniverse.com>, Cyrus Daboo <cyrus@daboo.name>, Mark Nottingham <mnot@mnot.net>, "Thomson, Martin" <Martin.Thomson@commscope.com>, HTTP Working Group <ietf-http-wg@w3.org>


On 3/25/2011 8:34 PM, Bill Burke wrote:
>     The only thing it doesn't seem to support is composing
> signatures from other signatures. I see this being a very useful feature in
> workflows where somebody needs to verify that more than one party saw the same
> representation.

Can you clarify the details of the added functionality you are interested in?

By way of guessing, I'm thinking of two possibilities of what you might have in 
mind:

1. A new signature covers an existing signature.  I think the DOSETA model can 
cover this by specifying the existing signature's header field in the list of 
covered fields.

2. Re-using calculations from a first signature for forming a second one.  This 
would be the two hashes (content and content+header).  Something related to this 
idea has occurred to be, but only vaguely and I haven't done any work on it.


> The only thing I worry about DKIM is that it imposes a key management structure
> and infrastructure? The users I deal with will probably want to integrate with
> existing mechanisms to manage keys and look them up and to verify identity
> (which will probably be different per user).

Officially, the DKIM/DOSETA specs permit referring to a different key retrieval 
mechanism.  In practice I haven't heard of that being used.

More generally, it is certainly fundamental to gain clarity and agreement on the 
key management and certification model that is required.


>  Specially I want to apply this
> protocol to enterprise based systems rather than the typical
> Google/Yahoo/Twitter kind of thing.

Well, those large services certainly use DKIM, but I believe there is nothing in 
the design that is specific to large services.  On the other hand, the design 
certainly is biased towards operation across the open (public) Internet and it 
is certainly true that enterprise-based operation can permit a variety of 
alternatives that are not available across the open Internet.

To the extent that these requirements can be characterized and support for 
satisfying them gains rough consensus, I'm more than happy to participate in the 
effort to add the enhancement in Doseta.

d/
-- 

   Dave Crocker
   Brandenburg InternetWorking
   bbiw.net
Received on Sunday, 27 March 2011 13:49:38 GMT

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