A Trial Balloon to Ban Email?

[Justin]

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Roy M.Silvernail (2003-05-13 04:52Z) wrote:

> On Monday 12 May 2003 07:09 pm, Joseph Ashwood wrote:
> 
> > That one's easy. Use a problem that is not in P but is in NP. To
> > make it clearer to most people, use a problem that can be verified
> > cheaply, but that can't be solved cheaply. 
> 
> Please permit me to join the dense crowd.  Now that I've proved my
> labor, how do I attach the proof to the email?  Obviously, some parts
> of the message are added to a hash, but which parts? If it's the body,
> is whitespace damage still an issue?

The message-id would need to be included.  Lots of people filter
duplicate messages, and those who don't probably should.  If spammers
try to replay, their duplicates get dropped.  If they don't reply using
the same message id, they're forced to regenerate hashcash tokens.
Using duplicate message ids is an RFC violation, and just using those in
the hash avoids the complication of mangled message bodies.  It also
gets rid of idiot MUAs which don't include message ids.

The mess seems to occur when considering how to verify that that
particular message, with a particular message id, wasn't bcc'd to) to 10
billion other people.  How do you determine whether a Delivered-To
header, if a mail server was even nice enough to indicate which envelope
to: address it used in the history of a message instance, indicates a
mailing list or an individual?  How do you know whether any hashcash
token that may have been generated based on a particular envelop to:
address is valid or corresponds to a delivery list with so many people
that the hashcash should be invalidated and whitelisting required?  If
envelope to: addresses are not each required to have separate hashcash
tokens, doesn't the whole scheme fall apart?

I don't know that including a Date: header in the hash improves the
situation.

- -- 
Freedom's untidy, and free people are free to make mistakes and commit
crimes and do bad things.  They're also free to live their lives and do
wonderful things.   --Rumsfeld, 2003-04-11
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