On Sun, 6 Jan 2008 05:38:52 pm SM wrote:
> At 02:12 05-01-2008, Andrew Haveland-Robinson wrote:
> >No, not relying on gmail, just noticed it didn't verify. Perhaps signed
> >messages should be delimited to protect against appendices, and made clear
> >where the authentication begins and ends?
> >Like the OSI 7 layer model, can't dkim not make use of wrappers and
> >encapsulation to preserve integrity during transmission/forwarding?
>
> There's an option (BodyLengths ) which will include the body length
> tag when signing a message.  This allows the message to pass
> verification if it goes through a mailing list which append a
> footer.  DKIM-signed messages are generally not affected by
> forwarding as the signed headers and body content is not modified by
> forwarders.

I did a trial patch to enable a database of addresses that will receive the 
body length tag. Database entries need to be managed using raw db tools (ref 
comment "2007-11-03 23:29").

http://sourceforge.net/tracker/index.php?func=detail&aid=1811969&group_id=139420&atid=744361

For other email lists, like this one, you need to account for the [listname] 
tags.

my opinion is that gracefull handling of email lists fudges will ultimately 
determine if DKIM is readily adopted in an organisation.

perhaps the verification process could almost brute force the email list 
mangles. This would involve:
1. attempting the subject line unfudges (removing []) 
s/Subject:/\([^[]*\)\[[^\]*] \?\(.*\)/\1\2/'
2. attempting to remove the last 5 (configurable) lines off the email and see 
if that passes.

Yes this going to be really ugly to implement. Is it worth it?

Am I missing something in the standard that says a verifying server should not 
attempt to verify the original signature?

-- 

Daniel Black
--
Proudly a Gentoo Linux User.
Gnu-PG/PGP signed and encrypted email preferred
http://pgp.mit.edu:11371/pks/lookup?op=get&search=0x76677097
GPG Signature D934 5397 A84A 6366 9687  9EB2 861A 4ABA 7667 7097

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