[ietf-dkim] New Issue: overview document does not mention message validity

[J D Falk]

Suggested addition to section 2, though I'm not entirely certain that
"validity" is the correct word to use here:

2.3.  Establishing Message Validity

   Though man-in-the-middle attacks are historically rare in email,
   it is nevertheless theoretically possible for a message to be
   modified during transit.  An interesting side effect of the
   cryptographic method used by DKIM is that it is possible to be
   certain that a signed message (or, if l= is used, the signed
   portion of a message) has not been modified.  If it has been
   changed in any way, then the message will not be verified
   successfully with DKIM.

   As described above, this validity neither lowers nor raises the
   level of trust associated with the message.  If it was an
   untrustworthy message when initially sent, the verifier may be 
   certain that the message will be equally untrustworthy upon 
   receipt and successful verification.

--
J.D. Falk
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