Re: how many bits / how to negotiate (Re: Re: stampcreation std. deviation)

> Adam Back wrote:
>
>> Jonathan's fast minter does ~4 Megahashes/sec or about 22 bits/sec on
>> a 3Ghz P4.  But I concur: I think 20 bits is about right now also.
>
> eric wrote:
> but you're talking about a stamp of under a second.  That's really way
> too short.  You are only looking at degrading spammer performance by
> 50(ish).  If you use a 15 second stamp, you are degrading to performanc=
e
> by 750(ish).  the smaller stamp also makes the zombie argument more
> viable.
>

As a reference point; http://www.hashcash.org/papers/proof-work.pdf (page
5) Calculates spammer profitability breakeven point at about 50 seconds
per email.

Microsoft CSRI paper at:
http://www.microsoft.com/mscorp/twc/privacy/spam_csri.mspx uses a slightl=
y
different method, but calculates the breakeven point at 60 seconds.