Subject: [ietf-dkim] RFC4871bis - whether to drop -- h: Acceptable hash algorithms

From: Dave CROCKER <[email-masked]>
Date: Sat, 30 May 2009 10:15:12 -0700

Folks,

In:

   <http://mipassoc.org/pipermail/ietf-dkim/2009q2/011959.html>

Steve Atkins posted a list of suggested DKIM features to drop.

This note is intended to anchor a discussion thread for discusses one of those
features, namely:

>    TXT RR tags
> 
>      h: Acceptable hash algorithms
> 
> The spec needs to define the supported set of hash algorithms. There  
> may be some value in a signer being able to state that they're using  
> an algorithm that isn't supported, perhaps.
> 
> But unless there is a viable attack such that an attacker can craft a  
> message that validates correctly against the domain owner public key  
> using a hash supported by the spec (sha1 or sha256), without access to  
> the domain owners private key, then there's no need for this to be in  
> the TXT record.

Please discuss arguments for and against dropping this.

d/
-- 

   Dave Crocker
   Brandenburg InternetWorking
   bbiw.net

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