ietf-dkim
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Re: [ietf-dkim] Ticket #17

2011-04-26 21:44:53
Douglas Otis wrote:
On 4/26/11 2:03 PM, Dave CROCKER wrote:

This ticket is invalid.

Dave,

When DKIM allows garbage input, DKIM's output is also garbage and 
untrustworthy.  The saying Garbage-IN Garbage-OUT is still valid.  Fake 
A-Labels can still resolve resources satisfying DKIM's signing 
algorithms.  Cryptography only indicates some odd domain published a 
public key matching the key used to sign a message.  The A-Label concern 
will become more apparent when UTF-8 encoding is generally permitted 
within email.

As an developer, I am mostly concern with the process functional 
"blackbox" implementation modeling aspects and that comes with the 
engineering faith the functional specification and the I/O were well 
considered.

For RFC4871:

    dkim.sig.dvalue = EncodeRFC3492(dkim.signer.domain)

For RFC4871bis:

    dkim.sig.dvalue = EncodeRFC5890(dkim.signer.domain)

I don't see any software engineering issue other than to considered 
backward compatibility:

   dkim.signer.domain = DecodeRFC5890(DecodeRFC3492(dkim.sig.dvalue))

So all that is the easy part.  But I would love to see an example of 
what we are dealing with both RFC3492 and RFC5890 and see what these 
labels will look like.

Can you provide a few example maybe showing how an IDN address and 
domain will look like under each RFC and also UTF8 for?

    From:
    DKIM-Signature: d=
    DNS zone record

or anything else you deem important to show the issue and/or conflicts?

-- 
Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com


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