ietf-dkim
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Re: [ietf-dkim] Certifying the DKIM public key?

2011-05-22 12:29:56
through a separate, value-added mechanism.  My own preference would be for 
using
a special header-field that contains the cert, with the specification of 
using
such certs as saying that they are enabled when included in the set of h=
covered header fields.

I don't see how this is functionally different from VBR.  In both cases 
the signer assserts that the message is certified by foo.  If the 
recipient finds foo to be credible, it checks to see if foo really did 
certify the signer, by a DNS lookup for VBR, or I suppose by checking the 
offered cert to see if the signature is valid, and if the contents include 
the signer's domain and an expiration date in the future.

It occurs to me that since mail certification is likely to make assertions 
about behavior as well as identity, the SSL model in which certs last for 
a year won't work, since behavior can change rapidly.  Either the 
certifier has to issue a stream of short-term certs to everyone it 
certifies, or the verifiers have to check CRLs, which is tedious.  By the 
time you do all that, a DNS check, even one with DNSSEC, looks pretty 
attractive.

Regards,
John Levine, johnl(_at_)iecc(_dot_)com, Primary Perpetrator of "The Internet 
for Dummies",
Please consider the environment before reading this e-mail. http://jl.ly
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