ietf-dkim
[Top] [All Lists]

Re: [ietf-dkim] New canonicalizations

2011-05-17 12:46:47
Ian Eiloart wrote:
On 16 May 2011, at 14:26, Alessandro Vesely wrote:


Yes, http://www.opendkim.org/stats/report.html#hdr_canon says

Header canonicalization use:
canonicalization     count   domains passed
simple                  653688       6786    591938
relaxed                 3940377      56621   3640854

It does, but how does one interpret that? Certainly the weight of relaxed 
versus simple passes implies a user desire for relaxed canonicalisation.

However, the 90% versus 92% is meaningless without making certain 
assumptions. If all these messages were originally properly signed, then the 
2% represents a 20% reduction in false negatives, but only if we assume that 
canonicalisation method was selected at random or that choice of 
canonicalisation method was statistically independent of the likelihood of 
breakage - the latter might be plausible.

However if some of the messages were never properly signed (whether failed 
attempts to spoof, or administrative or technical failure), then that 20% 
must be higher. It could even represent 100% reduction in false negatives due 
to (otherwise benign) in-flight modifications.


What it seems to indicate to me is that its the common trait when 
isolated to the domain or domain organization.  IOW, the similar 
passage rate is a reflection of a domain implementation and 
verification pattern.

For example, a single person subscribed to two list and submitting the 
same message to two different list (i.e. a CC to a second list):

     LIST1 - DKIM AWARE, RESIGN
     LIST2 - DKIM NON-AWARE

can expect to see 100% pass with LIST1 but 100% fail with LIST2.

This tangent thread started with LIST2 did no body changes except for 
what it normally did of adding an extra line after the header and 
before the body.

The document editor and others believe this is a MLM BUG.  It could 
be, but we don't know if its really an normal attempt to add HEADER 
text that was empty:

Create List Message for Distribution:

     Body = EMPTY;
     Body +=  AppendText(GetHeaderNoticeForList()) + CRLF;
     Body +=  AppendText(GetMessageBody()) + CRLF;
     Body +=  AppendText(GetFooterNoticeForList()) + CRLF;

We just don't know. Of course, for programmers, one can easily see 
that there is a "mite" there where extra CRLF will be added.  We 
recognized it with the ending CRLF but "forgot" that list header text 
was also possible.  The key point is for "40" years, it wasn't a 
problem until a new kid in the block came and now demands MLMs adjust 
to work with it

-- 
Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com


_______________________________________________
NOTE WELL: This list operates according to 
http://mipassoc.org/dkim/ietf-list-rules.html