Re: anti-spam WKBIs, Worsening google service reputation and abuse

[Matthew Petach via NANOG <nanog () lists nanog org>]

On Sat, Aug 16, 2025 at 6:16 PM Damian Menscher <damian () google com> wrote:

> On Sat, Aug 16, 2025 at 6:08 PM Matthew Petach via NANOG <
> nanog () lists nanog org> wrote:
>
> > On Sat, Aug 16, 2025 at 5:47 PM John Levine via NANOG <
> > nanog () lists nanog org>
> > wrote:
> > > It appears that Matthew Petach via NANOG <nanog () lists nanog org> said:
> > > > I think we should take a cue from cryptocurrencies, and have a "proof
> > of
> > > > stake" type of
> > > > challenge for email messages sent out.  The recipient machine doesn't
> > > > accept a message
> > > > until the sender has demonstrated they have put some skin in the game
> > as
> > > well.
> > >
> > > Dwork and Naor invented that in 1992.  Clever idea, doesn't work in
> > > practice.
> > >
> > > https://www.wisdom.weizmann.ac.il/~naor/PAPERS/pvp.pdf
> >
> >
> > OK, I read the paper through, and they put considerably more thought into
> > the calculation side;
> > however, this paper explicitly calls for a centralized Pricing Authority,
> > which is exactly what I'm
> > advocating *against*.
> >
> > And this would, in my opinion, be why it's a non-starter.  You'll never
> > get
> > a system
> > that requires everyone to adhere to dictates from a central authority.
> >
> > Instead, I'm advocating for a decentralized, one-at-a-time type approach,
> > where the penalty box is in the time domain, so it's easily implemented
> > unilaterally by the receiving side.  It's the very opposite of what the
> > paper you're citing proposed.
>
> Pretty sure what you're proposing is the equivalent of Hashcash?
> https://en.wikipedia.org/wiki/Hashcash

Ah, very cool!  I wasn't aware of that, thank you for the pointer to it!

I'm not sure that needing to maintain a database of used hash values would
scale very well, though, but I like that
it made it into SpamAssassin for a while.  The need to manually configure
address resources/domain patterns
in order for it to be enabled sounds like it may have limited the scope to
which it got applied, but that sounds
like it was very similar to what I was thinking.

Good to know smarter minds than mine already came up with it and tried it
out.  ^_^;

Thanks!

Matt
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