Scott Robinson wrote: > How does hashcash stand up to Moore's law? How is this not a temporary > solution? http://www.camram.org/frequently-raised-objections.html question 5 although as I was rereading what I had written, I think this elaboration may also help. all proof of work puzzles be it memory or computation will eventually degrade to the same thing courtesy Moore's Law. All you are doing is exercising the number of transistors you can pack onto a chip. The only way to cope with Moore's Law is through a mechanisms of communicating local coverage postage rates. Local as defined by the people you communicate with. If you know the rates expected by all of your peers, your own processing capability, and the stamp values of any spam, you can then set your own rate. and yes, this does imply a need for some form of insufficient postage mechanism. It will probably need a trigger which won't fire unless the incoming postage is within three bits of your rate. this trigger is so the spammers can't jojob easily. If you're worried about the low-end systems being locked out because of long computation times, in the camram implementation, I'm not sending stamps unless they are to people I don't know. Which lets me generate a much bigger stamp because I'm not doing it as often. I also get additional immunity from stamp size by generating stamps in background. You don't have to sit there waiting for the stamp before you can move onto the next message. ---eric