[Mailman-Developers] Mailman headers roundup

[Chris Clark]

Barry Warsaw wrote:
> On Oct 30, 2011, at 08:04 PM, Patrick Ben Koetter wrote:
>   
>> X-Message-ID-Hash
>> 	propose an RFC as an extension of RFC 5064
>> 	Modify to: unclear
>> 	Next Step: Discuss
>>     
>
> As an RFC, obviously we'd drop the X- prefix, but also "Hash" might be too
> vague.  Personally I think Message-ID-Hash is fine and the theoretical RFC
> shouldn't allow much leeway in implementations (i.e. only one hash algorithm
> is allowed).  This will probably be bikeshedded to death.  Still, since
> Message-ID must be unique (and generally is, as backed up by The Mail
> Archive's data), I think base-32 of SHA-1 will in practice be just fine.
>   

I love painting bikesheds... or rather offering paint color/colour 
suggestions to painters doing the work ;-)

If a header is going to contain data that is generated from non-trivial 
processing I think it would be good form to include the algorithm name 
in the header.

The DKIM-Signature (RFC 4871, and was included in the email I'm replying 
to) itself includes the name, example extract:

    DKIM-Signature: a=rsa-sha256; .........

DKIM is using a secure hash which is arguable more processing than a 
simple digest hash but the same principle of self documenting seems 
reasonable.

Admittedly there will be a need in the future for new secure algorithms 
to be deployed for DKIM, it is less certain if there is a need to ever 
change the algorithm used for X-Message-ID-Hash. Is there a clear 
advantage limiting the algorithm used?

Chris