[ietf-dkim] Postfix: change of Content-Transfer-Encoding breaks DKIM signature / RFC recommendation

[Florian Sager]

>> According to the mails below the RFC compliant change of content
>> encoding in MTA-forwarding may break signatures that follow the RFC 4871
>> recommendation to include header "Content-Transfer-Encoding" in the
>> signature. This header should be removed from section 5.5. Recommended
>> Signature Content (The following header fields SHOULD be included in the
>> signature ...).
>>     
>
> Unfortunately, this does not solve the problem.  The 8bit-MIME to
> 7bit conversion as required(*) in RFC 1652 replaces the entire
> message body, and therefore it invalidates DKIM signatures even
> when the Content-Transfer-Encoding header is not signed.
>   
Well, I thought the canonicalization would reduce the encoding problems
but I didn't check this.
I expect if a redesign of DKIM would take place an improved
canonicalization method could solve this problem?

Florian