spf-discuss
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Re: Andy Newton says: FTC Dismisses SPF

2005-06-25 08:23:13
 SES is effectively just BATV with a slightly different
 syntax,

No.  SES is more different than that.


In looking at:

   "The Signed Envelope Sender (SES) Protocol"
   <http://ses.codeshare.ca/files/Working_SES_Format_Definition_16.pdf>


Section 1.
....
    Recipients of SES signed messages can verify the
 return-path and in most cases the 2822 sender address by requesting
 validation from each sending domain.

and

Section 2.
....
 The digest signature validates the return-path and
 ensures that the message headers and body are the same ones originally
 sent with that return-path.


BATV pertains to the rfc2821.MailFrom command and has nothing at all to do
with any RFC2822 header content.

SES's attempt to correlate the MailFrom address with anything else is a
basic difference from BATV.

We could also explore SES's much more elaborate signing algorithm, but since
BATV is extensible, it's not much of a stretch to imagine someone adding a
scheme on the order of what SES uses.

On the other hand:

Section 5.4
....
     The service is
 through custom UDP server, DNS or SMTP, as designated by the sender in
 the V character of the SES-signed return-path.

The requirement for cross-net query, in order to perform validation, is
massive increment in overhead from the basic algorithm used by BATV.

The barrier to adoption is a fundamental concern for new protocols, and the
requirement for the cross-net query is at least a quantum higher barrier
than BATV imposes.

  d/
  ---
  Dave Crocker
  Brandenburg InternetWorking
  +1.408.246.8253
  dcrocker  a t ...
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