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Re: [ietf-dkim] Is anyone using ADSP? - bit more data from the receiving side

2009-10-13 04:39:30
Dave CROCKER wrote:


Steve Atkins wrote:
The "brand" cannot be protected solely via ADSP, at all, not in any manner.

By that I mean that it's possible to protect the byte sequence paypal.com to
some limited degree, but that that is operationally meaningless without any
way to distinguish between "paypal.com" and "paypa1.com", or between
"citibank.com" and "citibankonline.com", 


If anything, Steve is being generous, because it's actually muss worse than 
that...

The name variants are one line of attack, with respect to the From: field 
address - which is what's being discussed here.


We are taking about Domain spoofs, not phishing.  There are two 
different set of problem and there was long agreement that DKIM or 
POLICY can protect against phishing.

This is about domain spoof protection and nothing more.

But then there are all the attacks on the From: field visible name -- which 
is 
all most recipients ever see -- the Subject line attacks and the Body 
attacks. 
None of these is even touched by an ADSP approach.


and no one ever engineered any of the proposed Policy Protocols, from 
SSP to ADSP, to address mail alterations as you described. That is 
what DKIM-BASE is suppose to do.  However, see below.

When someone asserts that a mechanism offers protection, they are obligated 
to 
account for the cases that are /not/ covered.  


Dave, this is a false premise because you are indicating concepts that 
were never designed to be part of any policy protocol proposal.

If they are diligent, they will 
then assess the relative costs and benefits of this protection proportion, 
versus the unprotected proportion.

Again, Policy, since day one, was about Domain Signature practices. 
Not about domain phishing nor mail integrity changes.  However, since 
mail integrity changes are possible reasons for a policy violation, 
as RFC 4871 mandates:

      invalid signature is promoted as no signature

this allows POLICY and specifically ADSP DKIM=DISCARDABLE to offer 
high protection for Author Domains who expect protection against 
Domain Spoofs and Mail Integrity Violations at DKIM/ADSP supportive 
receivers.

This issue here is whether intermediary signers are obligated to also 
support unauthorized 3rd party signing protection sought by ADSP domains?

--
HLS



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