[Libdkim-discuss] DKIM problem

[Peter C. <co...@qu...>]

Hi,

I've run into a curious compatibility problem with Mail::DKIM and
libdkim from libdkim.sf.net.

I've created a DKIM-signed mail using Mail::DKIM (see the attachement).
According to http://www.brandonchecketts.com/emailtest.php (which uses
Mail::DKIM, too), the signature verifies OK. libdkim tells me the signature
fails to verify.

Apart from the problem that libdkim requires a signed subject header in its
default configuration, the real problem is the folding whitespace immediately
after the "b=" in the DKIM-Signature header. Apparently, the signature doesn't
include the FWS, but libdkim does include it for verification.

IMO RFC-4871 is not clear on which behaviour is correct. Section 3.4 mandates
that for "simple" canonicalization all whitespace is to be preserved, while
section 3.7 requires the value of the "b=" tag to be removed for verifying.
It is unclear if the FWS between tag and value is to be removed or not.

Any ideas?

Thanks,
	Peter