So, we would need about 44 hours of CPU time each day.
Well, have a system of certified remailers trusted to force their users to burn up time at the sending end, so the ultimate recipient accepts their messages w/o postage. One certified remailer accepts messages from others without any postage, so only the original sender has to use up CPU time. ... Since we need hashcash now to LEAVE a remailer, not to enter one, where does this hashcash come from? A busy remailer could not generate it's own hashcash for the destination non-remailer ISPs.
This is exactly what I was addressing: remailers only have to get themselves certified as remailers and then prove their certification to the destination server, not do the whole hashcash shtick for every message. (For example, they could publish their public key's hash signed by some anti-spam organization, then sign the hash of the server's challenge to prove that they are a real remailer, not an advanced spammer imitating one)
Does the same hashcash that allows a message to enter the remailer network also retain it's validity once the message has been rewritten by the remailer? Is this hashcash still valid for the destination mail server at netcom? Does the initial sender provide two instances of hashcash, one to get into the remailer, and one to get into the destination mail system?
Nope. The original sender provides hashcash to get into the remailer net, and the receiver, after seeing the remailer's certificate, trusts that the original sender spent some CPU time to send the message. The remailer doesn't have to while away nearly as much of *its* CPU time, and spammers still couldn't send many messages since they still have to waste their CPU cycles to do so. ...
-- Robert Costner Phone: (770) 512-8746 Electronic Frontiers Georgia mailto:pooh@efga.org http://www.efga.org/ run PGP 5.0 for my public key
--------------------------------------------------------------------------- Randall Farmer rfarmer@hiwaay.net http://hiwaay.net/~rfarmer