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Re: [ietf-dkim] Re: What the verifier can do

2006-04-30 12:33:16
Tony Hansen wrote:

Paul Hoffman wrote:

Paul, which hash where? There is no hash in the dkim signature for the
headers, only a hash for the body and the resulting signature.

Now, *if* there were a header hash in the signature, each of your other
steps 2-4 would be accurate. But there isn't, which is why the algorithm is:

  1)    calculate the body hash
  2)    verify the hash of the body
        2a) if desired, apply heuristics to body and repeat from 1
  3)    verify the signature using RSA
        3a) if desired, apply heuristics to headers and repeat from 3
If you're going to apply heuristics to the headers, you can't get away
from recalculating the RSA signature after each application of the
heuristics.
I think you're both saying the same thing. The RSA verify operation yields
a hash that you compare against the hash of the headers (and body from bh).
I think that's what Paul is referring to.

      Mike
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