ietf-dkim
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Re: [ietf-dkim] New canonicalizations

2011-05-23 08:42:21
Charles Lindsey wrote:

On Mon, 23 May 2011 03:50:06 +0100, Hector Santos 
<hsantos(_at_)isdg(_dot_)net> wrote:

It would of been nice to have some DKIM-Signature flag that might
indicate the Content-Transfer-Encoding, i.e.:

    et="base64"   <--- copy of the top level Content-Transfer-Encoding

Could you get the effect of this by including the  
Content-Transfer-Encoding header in the 'h=' and doing some fancy checks  
involving the 'bh=' (to detect whether it was the body or the headers or  
both that were broken)?

Using the currently defined standard specification, the only way to do 
a reliable check is to add the z= header which contains the values of 
the h= header fields.  However, having z= is more for testing, can be 
exploited in some fashion and adds ugly DKIM-Signature bandwidth 
overhead.  So its not a good idea, I think, for everyday usage.

But since DKIM is "flexible" :),  adding maybe an et= tag should not 
break the system allowing for exploration to see if that could help 
lower failures for some streams.

In this test case with the gmail.com message submitted to a non-DKIM 
aware list, it would of succeeded knowing the original top level 
encoding type and using l= if destined to a list.

I think the other side point in my OP, is that it didn't seem it was 
necessary to base64 the message content.  I saw no 8 bit characters 
when I decoded it - just plain 7bit ascii.  So it seems some systems 
are always doing it regarding of 7/8 bit.

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


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