authentication & cash (Was: The issue of mime parsing)

clemens fischer (Thu, Apr 03, 2003 at 10:12:42AM +0200):
> Stefan Karrmann <[email protected]>:
> 
> > Then BI or (later on) the addressee can get the message
> > securely. IM2k should not require that every message is
> > authenticated. This should be the addressee's choice.
> 
> and i think im2k should require every message to be authentic(ated).

How should anonymous mail work in im2k?

> > Please note that the list of alternative cash kinds is optional. And
> > a kind of cash may be hashcash, i.e. you may have only to spend some
> > spare cpu-cycles. If IM2k supports a challenge response cash system
> > you need only to spend it if its required by the addresse (or drop
> > your message).
> 
> so do you think potential receivers should be able to reqire me to
> participate in SETI@home, or do gene analysis?  well, i'd drop each
> of those messages, because what seems SETI to me may just be some
> specific encoding of some government agencies key cracker or attempt
> to make better soldiers.  if you want to donate or make available
> spare CPU cycles, from inside an email protocol, you will have to
> provide a specification for it.  this is different from im2k and
> should not be part of it.

In hashcash you have to spend some CPU cycles to get a collision of
k bits in n bits after applying a well known hash algorithm like SHA.
You don't have to run a suspicious program. If the receiver wants cash
that you are not willing to pay, the message will not be delivered and
im2k should inform you explicitly about this.

Sincerely,
-- 
Stefan Karrmann