what fields to hash with hashcash (Re: A Trial Balloon to Ban Email?)

[Eric S. Johansson]

R. A. Hettinga propagated:

> --- begin forwarded text
> 
> 
> Date: Wed, 14 May 2003 16:34:23 +0100
> From: Adam Back <adam at cypherspace.org>
> To: cypherpunks at einstein.ssz.com
> Cc: Adam Back <adam at cypherspace.org>
> Subject: Re: what fields to hash with hashcash (Re: A Trial Balloon to
>   Ban Email?)
> Sender: owner-cypherpunks at lne.com
> 

>>Worse, even if there were a reliable mechanism, all it takes is one
>>loose cannon with an open mass-mail list and as long as it doesn't
>>delete whatever header (maybe delivered-to:, maybe something else) that
>>indicates the list was an envelope to: address, one hashcash token works
>>for one email to the entire list.

actually, no it doesn't.  The real, working code has a configuration file which 
contains a list of all known addresses associated with the account.  That list 
of addresses is necessary because of people having virtual domain based 
addresses collecting all at 1 mailbox.

The code uses that list of valid addresses in the stamp validation process.

> I take it this comment is about mailing lists?  Mailing lists have to
> be treated separately.  The sender probably can't afford to create a
> token for each recipient.  (Also he doesn't know the recipient's
> addresses).  Mailing lists deal with spam with filtered versions of
> lists.

mailing lists are your "friend".  While I don't have the code in there yet, I 
expect I will need to pay attention to the -request form of addresses and white 
list both the -request form and the plain form for a while.  Ideally, the 
mailing lists would sign each message with its own private key and use the white 
list by public key filtering method client side.

while I know this is the cypherpunks list, but if you ever get tired of debating 
this to death and would like to write some real code, let me know.  ;-)

---eric