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Re: [ietf-dkim] New Issue: note on figure in overview draft

2008-03-23 14:36:55
Double mumble.

Jim,

Per the response to Levine's concern, I'd rather simply have text that dodges 
the question of multiple signatures, here.  Multiple sigs are fine, but the 
figure is trying to look at a more contained topic.  I believe that having the 
figure explicitly show multiple sigs will, for example, require showing 
multiple 
private/public key pairs, and probably some sort of iterative behavior to cycle 
through each key.  Since this is an architectural diagram, rather than a 
functional flow chart, I don't think the complexity of iteration is needed.

Can you live with that?

Here is the complete section:


             <artwork name="DKIM Service Architecture"><![CDATA[
                              |
                              |- RFC2822 Message
                              V
+--------+   +--------------------------------+
| Private|   |  ORIGINATING OR RELAYING ADMD  |
| Key    +..>|  Sign Message                  |
| Store  |   +---------------+----------------+
+--------+                   |
  (paired)                    |
+--------+                   |                 +-----------+
| Public |                   |                 | Remote    |
| Key    |               [Internet]            | Sender    |
| Store  |                   |                 | Practices |
+----+---+                   |                 +-----+-----+
      .                       V                       .
      .       +--------------------------------+      .
      .       |  RELAYING OR DELIVERING ADMD   |      .
      .       |  Message Signed?               |      .
      .       +-----+----------------+---------+      .
      .             |yes             |no              .
      .             V                |                .
      .       +------------+         |                .
      +......>| Verify     +-----+   |                .
              | Signatures |     |   |                .
              +-----+------+     |   |                .
                pass|        fail|   |                .
                    V            |   |                .
                +--------+       |   |                .
      +........>| Assess |       |   |                .
      .         | Signer |       V   V                .
      .         +---+----+     +-------+              .
      .             |         / Check   \<............+
      .             +------->/  Signing  \
      .             |       /   Practices \<..........+
      .             |      +-------+-------+          .
      .             |              |                  .
      .             |              V                  .
+----+--------+    |        +-----------+     +------+-----+
|Reputation/  |    |        | Message   |     | Local Info |
|Accreditation|    +------->| Filtering |     | on Sender  |
|Info         |             | Engine    |     | Practices  |
+-------------+             +-----------+     +------------+]]>
             </artwork>
          </figure>
          <t>As shown in <xref target="DKIMSvc" />, basic message processing is
             divided between a signing Administrative Management Domain (ADMD)
             and a validating ADMD. At its simplest, this is between the
             Originating ADMD and the delivering ADMD, but can involve other
             ADMDs in the handling path. <list style="hanging">
                <t hangText="Signing"> Signing is performed by an authorized
                   module within the signing ADMD and uses private information
                   from the Key Store. Within the originating ADMD, this might 
be
                   performed by the MUA, MSA or an MTA.</t>
                <t hangText="Validating"> Validating is performed by an
                   authorized module within the validating ADMD. Within a
                   delivering ADMD, validating might be performed by an MTA, MDA
                   or MUA. The module verifies the signature or determines
                   whether a signature was required. Verifying the signature 
uses
                   public information from the Key Store. If the signature
                   passes, reputation information is used to asses the signer 
and
                   that information is passed to the message filtering system. 
If
                   the signature fails or there is no signature, information
                   about the related signing practices is retrieved remotely
                   and/or locally, and that information is passed to the message
                   filtering system. </t>
                <t hangText="Note:"> By virtue of showing a single 
private/public
                   key pairing, <xref target="DKIMSvc" /> can be taken to refer
                   to a single message signature. The figure is not intended to
                   comment upon single vs. multiple signature and merely shows
                   the sequential relationship between a signer and a validator
                   and their functional components. </t>
             </list>
          </t>




Jim Fenton wrote:
John Levine wrote:
At the end of section 5, just before the header 5.1 (page 15 of the txt
version) it says:

   Note:  Figure 1 does not show the effects on the message handling
      when multiple signatures or non-author signatures are present.

By my reading, fig 1 covers all signatures, single, multiple, author,
or otherwise, e.g., in the figure it says Verify Signatures with
Signatures in the plural.

Suggested fix: delete the note.
  

I'm still having a little trouble with Figure 1.  The box that says 
"Verify Signatures" has a "pass" and "fail" output; does that mean "one 
or more signatures pass", "all signatures pass", or what?

This might be addressed by following "verify signatures" with a decision 
box that says "Valid signatures?" with outputs "none" and ">= 1".  This 
might even replace the "Message signed?" decision box.

I had been thinking it would be nice to have a decision box to see if 
the valid signatures are author signatures for all authors, but I'm OK 
if that is lumped into "Assess Signer" (which should really be "Assess 
Signer(s)").

Also please note that Eric's comment on terminology in the Section 5 
intro (with which I agree) applies to Figure 1 as well.

-Jim

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-- 

   Dave Crocker
   Brandenburg InternetWorking
   bbiw.net
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