Re: Problems with SPF, solutions, and a timeline.

On 2004-02-28 10:37:27 -0500, Alan DeKok wrote:
> John Levine <[email protected]> wrote:
> > I'd like to stop getting bounce messages, too, but it sounds like
> > you're agreeing that LMAP schemes will not in fact deter any spam
> > since spammers can easily evade it by using either their own throwaway
> > domains or any of the millions of domains that will never publish LMAP
> > records.
>
>   The same argument can be applied to any proposed anti-spam system:
> There are tens of millions of systems which will never publish
> anti-spam information "foo", or will never clean the spam trojans off
> their systems, or will never fix their open proxy, or will never do
> anything.

That's a different problem. Sure, there will always be such systems. The
question is whether we get enough legitimate mail from such systems to
bother. If we do, then the anti-spam system won't be much good - tough
luck. But John's objection is on another level: If it doesn't stop spam
even if it is fully deployed, because spammers can simply publish LMAP
information like anybody else, then that scheme doesn't do what it is
designed to do (it may have some other benefit, like stopping bounce
messages, though).


>   This sounds to me like an argument for throwing away SMTP entirely,
> and starting over with perhaps a similar protocol on a different port,
> but one which doesn't have SMTP's flaws.

Which might be a good idea. It will take some time to catch on, but if
we look at the instant messaging or peer-to-peer protocols, users are
quite fast at accepting new protocols if they think it is worthwhile.

> > If so, why bother?  We should move directly to a signature scheme like
> > domain keys in which each protected message makes a directly
> > verifiable assertion that it's good,
>
>   And the spammers will (of course) sign their own messages, so such
> schemes are pointless, because all they do is make the recipient do
> more work, with no long-term benefit.

If you assume that signing alone will deter spammers, yes. Signing a
message with a private key K says nothing more than that the message was
sent by (or through) the holder of private key K. Of course a spammer
can invent any number of private keys, so in itself that's useless.

To make a signing scheme work, you need a scheme to express "trust".
Somebody has to certify that K is never used to send spam. This could be
some CA, but it doesn't necessarily have to be. Something like the PGP
web of trust or social networks like friendster or orkut would be
preferrable IMHO.

	hp

--
   _  | Peter J. Holzer    | I think we need two definitions:
|_|_) | Sysadmin WSR       | 1) The problem the *users* want us to solve
| |   | [email protected]         | 2) The problem our solution addresses.
__/   | http://www.hjp.at/ |    -- Phillip Hallam-Baker on spam

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