[ietf-dkim] Some very early implementation report details from OpenDKIM
tony at att.com
Wed Aug 4 11:32:05 PDT 2010
Very interesting data.
Too bad all of the domains with 100% failure rate are *all* hashed.
I'm surprised that failed(body) is zero. I would have expected that to
fail more often due to mailing list modifications.
Some possible enhancements:
*) It would be interesting seeing some of this data graphed against time.
*) Of the l= uses, how many were l=0 vs. l=some-other-value?
*) Can differentiation be made between syntax errors in the DNS entry
and syntax errors in the signature?
On 8/4/2010 2:00 PM, Murray S. Kucherawy wrote:
> We've started gathering data from a few of our installations that have
> chosen to submit it to us. With only four sources reporting, we can
> already see some interesting pieces of information.
> A report is generated based on our accumulated data every half hour at
> First, some explanation, as the reports are currently somewhat crude:
> - Each record in the database represents a single received message.
> - In the signature algorithm table, "0" is rsa-sha1, "1" is rsa-sha256.
> - In the two canonicalization tables, "0" is simple, "1" is relaxed.
> - In the pass/fail rate tables, "failed(body)" indicates a message
> where "bh" changed between the signer and the verifier.
> - Data submitters are given the option to anonymize their data. This
> is done by MD5-ing the From: domain and the submitting IP address,
> allowing aggregation of data on common sources but only limited
> reverse-engineering of it. This is why the domain names in some cases
> are hashes and not real data.
> - Mailing list traffic is detected by identifying List-* header fields
> or a "Precedence: list" header field. If people have additional ways
> to suggest identifying list traffic, please let me know.
> - ADSP "passed" currently includes things with valid author domain
> signatures, for which ADSP is actually not checked. This will be
> broken out in our next release.
> The very interesting things to note so far:
> - "relaxed" is the most popular header canonicalization, but I think
> we expected that. "relaxed" is also the most popular body
> canonicalization, which is not the general advice we give, though I
> suspect this is skewed by the fact that that's what gmail.com uses.
> - Almost 90% of DKIM signatures survive, unless they go through lists
> in which case the success rate plunges to 32%.
> - Just under half of all signed mail passes through five hops total
> (some of which may be pre-signature).
> - Most DKIM signatures pass as long as they go through three or fewer
> hops. After that, survivability drops dramatically.
> - Not a single signature has failed as a result of body changes (apart
> from what the canonicalizations tolerate).
> - Third-party signatures appear to have a much higher failure rate
> than author signatures.
> Upcoming revisions to our collection mechanisms include:
> - Tracking use of "g=" in keys.
> - More detailed analysis of ADSP.
> - Tracking of DNSSEC use with respect to DKIM keys.
> - Ability to produce reports for each reporting site rather than only
> aggregation. (We can do that now but because of our current schema,
> it's expensive.)
> - Ability to exclude anonymized data from certain reports.
> - When "z=" tags are used, identification of which fields are being
> changed in transit.
> We need more data! OpenDKIM users are encouraged to enable the
> statistics code and participate in the program (though, of course, you
> are under no obligation to do so). Instructions were sent to the
> opendkim-users list on July 30th, as well as information already
> available in the stats/README file in the source distribution.
> Feedback from both groups is welcome.
> NOTE WELL: This list operates according to
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