Re: message dependent hashcash => no double spend database (Re: hashcash spam prevention & firewalls)

["Uhh...this is Joe [Randall Farmer]" <rfarmer@HiWAAY.net>]

...
> As a technological fix for spam, destination address hashcash seems to be
> lacking.  All this does is raise the wall of entry into becoming a
> spamhause from one PC to say, ten.  It is not much more difficult to sell a
> CD-ROM with one million email addresses & hashcash.   A 20 second hashcash
> expenditure on one million email addresses will take about 231 CPU days, or
> about three weeks if you use ten machines.  Sell 500 copies of the CD-ROM
						   ^^^^^^^^^^ 
Hashcash has a double-spending database to prevent this -- one use and you've
got to wait until it's out of the database (quite possibly a long time) before
you can reuse it.

...
> The implementation of the plan is a more or less impossible scheme. 

Nyet. It can be phased in over time...people install the software, mailing
lists warn their users to exempt them, and the big servers start asking for the
hashcash, little servers pick it up. 

...
> privacy problems with warehousing with your ISP a list of your other email
> addresses, or the addresses of your postage free friends.  

This's already been addressed.

> Changes to the "Don't charge postage" database will be awkward.  

Well, it wouldn't be much trickier than a Pine address book (few things are :) 
or a killfile.

---------------------------------------------------------------------------
Randall Farmer
    rfarmer@hiwaay.net
    http://hiwaay.net/~rfarmer