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[ietf-dkim] Concerns about DKIM and mailiing lists

2006-03-14 19:49:35
Taking my own advice:


Mailing list software takes delivery of a message and posts a new message. The new message might look almost exactly like the old one or it might look massively different.


1. Anyone who has concerns should express them to the list, succinctly and concretely.

If a signature includes a useful hash of the message, it cannot survive really extreme violence. Hence, a signature cannot reasonably survive transit through a mailing list that makes major changes to the message.

DKIM cannot survive transit through some mailing lists and it is not reasonable to make it try.


2. Anyone who believes there are (or should be) no concerns should express them to the list, succinctly and concretely.

Some lists merely add headers. Some lists merely add text to the body. These are quite common behaviors and they both are quite structured.

DKIM's body length counting mechanism and selective inclusion of headers in the signature hash are robust against such changes.

Some mailing lists can modify some of the body data encoding. DKIM's canonicalization choices provide a reasonable degree of robustness against such changes.

d/

--

Dave Crocker
Brandenburg InternetWorking
<http://bbiw.net>
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