[hashcash] Re: response to "proof of work proves not to work"?
- From: "Eric S. Johansson" <esj@xxxxxxxxxx>
- To: hashcash@xxxxxxxxxxxxx
- Date: Mon, 17 Jul 2006 16:57:09 -0400
John Honan wrote:
I've also done some calculations on spammer profitability and breakeven.
I used this approach;
If it takes x seconds for a spammer to stamp and send an email, then if
x is large enough it should be possible to impact the spammers
profitability enough to deter them from sending spam in the first place.
I think we're fundamentally coming from the same place. It's really
quite obvious when you think about it. :-)
When we work out what the spammers breakeven point is, we can then
derive how long it should take to calculate a Hashcash stamp to make
them unprofitable. There are only a certain number of seconds in a day,
which means the spammer is limited in the maximum amount of stamped
email they can send per CPU per day.
have fun with the calculator. Internal calculator is pretty badly
it's not the last. I've attached a slightly cleaner calculator. The
main difference being organization and that I have not tried to put any
sort of economic calculations into it. That we can add on.
You're right in that we have to make some assumptions about spam
response rates, profit-per-response and cost of running one CPU, but
this is the basic approach I took. Based on my calculations, I figured
the optimum stamp size to put a spammer out of business is 59 seconds -
or about a 30-bit stamp size on a fast processor; which brings up the
issue of cpu 'egalitarianism'....
I'd really like to take a look at your approach to the calculations
whenever you post them.
looking at zombie calculator 2, 3 million zombies at 100% efficiency
with 13 billion spam stamps required, each stamp would be 19 seconds.
If you instead dropped the pass rate to 10%, the stamp size climbs to
199 seconds (no surprise there). But since nothing operates at 100%
efficiency, if we drop efficiency rating to something more realistic
like 33% then we end up with a 66 second stamp.
The big question is what pass rate is spam or breakeven rate and that's
more of a marketing/cost analysis model than I can do right now. so if
any of us have significant others or friends of significant others that
can do marketing type work, this is where they can prove they're worth
I must add, we have no idea the number of zombies. The last time I saw
antispam calculations breaking out in the zombie contingent, the numbers
worked out to something like 40,000 zombies running four hours a day.
Not a huge number. With those kind of numbers, we could break spammers
with as little as a 0.7 seconds stamp. A 2 second stamp would wipe them
this is all assuming I didn't screw up my calculator. I've been
anyway, if the attachment does not make it through, let me know.
attack duration (hours)
zombie efficency rating (percent)
percentage pass rate
stamp volume demand per zombie per duration
stamp minutes (how many 1 min stamps zombies can send)
stamp size in seconds
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