Subject: RE: [ietf-dkim] Base issue: multiple linked signatures

From: "Hallam-Baker, Phillip" <[email-masked]>
Date: Thu, 4 Jan 2007 11:12:06 -0800

> From: John Levine [mailto:[email-masked]] 

> Subject: Re: [ietf-dkim] Base issue: multiple linked signatures
> 
> >>    Verifiers MUST NOT use the header field names or copied values
> >>    for checking the signature in any way.  Copied header field
> >>    values are for diagnostic use only.
> 
> >1) This condition is ACTUALLY REQUIRED for interoperation?
> 
> Well, yeah.  If the verifier is a separate module from the 
> one that sorts mail based on the verification result, the 
> sorter is going to act differently with results from a strict 
> verifier vs. a squidgy one.

Delivering a different result is not the same as incompatibility.

Is a signature verifier going to generate a result that is less likely to correctly reflect the authenticity of the message?

> >2) This condition limits actual HARM?
> 
> If we consider unwittingly accepting mail with bad signatures 
> as harm, yes.

This is an overt act that the recipient chooses to take.

Protection from an unwitting action is not justification for prohibiting taking the action with full knowledge. The point of SHOULD is to provide that knowledge.

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