[ietf-dkim] Protocol layering / Software vs. Protocol

[Douglas Otis]

On 5/4/11 10:01 AM, Dave CROCKER wrote:
> Folks,
> \
> In terms of working group process, one line of criticism demands re-opening
> (and, apparently, reversing) the work of the Update (RFC 5672).  I haven't seen
> any working group consensus to do this nor any industry feedback indicating this
> is necessary.  Consequently, attempts to pursue the content of that work is
> entirely out of scope for the current working group effort.
>
> There are two continuing threads of other, technical dissatisfaction being
> expressed that are based on fundamental misunderstandings of protocol design
> concepts.  The discussion on Wikipedia looks pretty good, for background:
>
>      <http://en.wikipedia.org/wiki/Network_protocol#A_basis_for_protocol_design>
>
> The easy misunderstanding is about the basic difference between software design
> and protocol design.  When a discussion is about a protocol specification,
> reference to the vagaries of software implementers' choices means that the
> discussion is no longer about the protocol.
>
> A protocol is a contract between two or more sides of an exchange.  The contract
> needs to be extremely precise so that all sides know exactly what is required
> and what is meant.  This includes semantics, syntax, and rules of exchange.
> Semantics means all of the meaning, not just the meaning of individual fields.
> And it means inputs and outputs.
DKIM is unable to _only_ consider signature confirmation and not also
expect existing email agents to not also adopt DKIM's unusual header
selection methods retro-actively. To be compatible with existing email
infrastructure and transparent to the fullest extent possible, one
can not expect new supporting infrastructure or modified clients;
This can *only* be achieved by some mandatory test within the Verifier.

-Doug