hashcash spam prevention & firewalls

Steve Schear schear at lvdi.net
Mon Dec 22 17:48:07 PST 1997



At 5:55 PM +0000 12/22/1997, Adam Back wrote:
>Bill Stewart <bill.stewart at pobox.com> writes:
>> >This is exactly what I was addressing: remailers only have to get
>> >themselves certified as remailers and then prove their certification
>> >to the destination
>> 
>> You're both taking the wrong approach - make the originator of the
>> message generate the hashcash, and make sure the remailer syntax
>> lets them paste it in as needed.  For chained remailers, generate
>> multiple layers of hashcash.  Maintaining whitelists is a losing
>> game, but unnecessary here.
>
>This works well enough.
>
>The more thorny problem to solve is that posed by Robert Costner: what
>do you do about nyms.  You (the sender) can't include postage for nym
>reply blocks because you don't know (and mustn't know) the remailer
>chain pointed to by the reply block.

eCache is probably the best solution for remailers (and probably SPAM in general) since real value can pass anonymously from sender to receptient.

>
>> Mailing lists are still hard, and perhaps best handled by the user's
>> software (or some fancy variant like user-selectable filters at the
>> ISP mailbox.)
>
>I think it's simplest to have the user explicitly allow the mailing
>list.

Yes, especially when the list requires a hashcash 'initiation,' before allowing unlimited postings, to prevent many  common list SPAM abuses.

--Steve








More information about the cypherpunks-legacy mailing list