Subject: Re: [Asrg] Email service assumptions and making system-wide changes

From: Douglas Otis <[email-masked]>
Date: Mon, 16 Jan 2006 17:08:55 -0800

On Jan 16, 2006, at 11:32 AM, Dave Crocker wrote:

> The nature of Internet applications is that they go through  
> incremental change over extended periods of time, both adapting to  
> changes in the environments and adding mechanisms to support added  
> functionality.  Much like a social process...
>
> Folks need to observe that the other global communications services  
> lack the kinds of authentication mechanisms that are so readily  
> claimed to be "essential" for today's proper Internet mail  
> operation.  That those other services have other features, which  
> tend to mitigate the abuses that dominate Internet mail, is a  
> matter of accident, rather than planning.
>
> On the matter of a redesign, we have two problems:
>
> 1.  It is not clear that it is needed.  Those claiming the need for  
> a redesign take it on faith that one is needed.  This is akin to  
> ready-shoot-aim. A re-design effort makes sense only after two pre- 
> conditions are met:
>
>    a) new requirements are formulated and gain community consensus,  
> and

DKIM is a good start, provided SSP is scuttled.  Constraints on From  
address will be highly disruptive, impractical to obtain, and yet  
easily circumvented by bad actors.  Perhaps at some point email  
readers and list-servers will accommodate a strategy where the From  
address represents a component of the transport, rather than the  
author of the message, but to what end?

Rather than depending upon super human vision, or the acquisition of  
thousands of look-alike domains by the various institutions, a  
cryptographic signature allows the recipient's email application to  
register and uniquely recognize a prior correspondent.  This source  
recognition models the innate ability of humans to identify a unique  
voice or a face.  By highlighting recognized sources, attempts at  
pretending to be one of these correspondents would be easily noticed  
by the lack of highlighting.

The signature also allows the signing-domain to include a non-spoof- 
able opaque-identifier that could be used to track the account used  
to gain access without introducing yet another email-address.  A  
large portion of spam is from compromised systems.  Providing third- 
parties a low cost solution to tracking such systems would be a  
positive step at overcoming this significant problem.  For example,  
there are many services that offer a free system scrub, but the  
account in trouble must be notified.  This type of opaque-identifier  
would also allow the recipient's email application to detect intra- 
domain spoofing without any administration and verification of  
specific authorizations of who can use what email-address.  Email- 
address freedom and independence can be retained using this approach.

> The heuristic I use for considering system-wide responses to spam,  
> and the like, is to ask whether the feature would be good to have,  
> even if abuses were not a major problem.  Hence, current abuses  
> serve merely as motivators.

Being able to recognize a prior correspondent should represent a  
desirable feature independent of the role this could play at abating  
abuse.  Source recognition also allows blocking the account, without  
expecting a miscreant to cooperate and always use the same email- 
address.

-Doug

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