From: zane@genesis.mcs.com (Sameer)
Date: Thu, 1 Jul 93 22:36:40 PDT
To: cypherpunks@toad.com
Subject: Junk email/encrypted return-path-blocks
Message-ID: <m0oBdbz-000MTeC@genesis.mcs.com>
MIME-Version: 1.0
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	I've been recently working at the direct-mail place putting rubber
bands around mass mailings of junk mail (ah, the wonders of being a poor
soon-to-be college student), which got me thinking about electronic junk
mail and how such a thing can be avoided.
	In rl, you can go to the store, buy a product with cash, and you're
not put on their mailing list. Buying via mail order, using
check/credit-card, etc., requires that they get your address so they can
put you on their mailing list, compile statistics about who you are,
etc., as we all know.
	Now, over the net, suppose I wanted to buy an email product. I'd
pay for it with digital cash, communicating with the vendor through the
anonymous remailers. Now I see a problem in how the vendor will deliver
the product. Obviously I can give the vendor my email address encrypted
with the remailer's public keys, so the vendor still doesn't know who I
am. But the vendor can still keep a database of address-blocks and which
address blocks go with which purchases. Then the vendor can compile her
mailing list of address blocks, and even *sell* this list to others,
with product purchase history. Even though the junk-mailers don't know
who I am, they can still flood my box with email.
	I thought of two possible solutions.

	The first solution I thought of requires a great deal of bandwidth.
The vendor could simply post publicly (to usenet or something) the
product I wanted, encrypted with my public key. (Rather, a public key I
created just for this venture with a psuedonym so that none could
see that it was I who was buying from the vendor.) The bandwidth for
this thing would be incredible.

	The second solution I thought of seems like it would work. When I
create the return-address block, it can be given some sort of ID-code
(again, like with my other idea posted, similar to the ID-code on peices
of Digicash in Chaum's scheme) so when the vendor delivers the product,
she sends to encrypted block to the remailer, and the remailer forwards
the product to me, and stores the ID-code in its database (doing the
proper one-way transformation for untraceability) so that further
attempts to use the exact same address-block will be noticed and not
delivered.

	I also thought of creating a digicash like entity, a currency to
pay for remailer transactions, so that sending junk mail through a
remailer would be prohibitively expensive. It will probably happen
anyway once we near the goal of full crypto-anarchy that most remailers
will not operate without a fee, while the scheme I present above seems
like it would work with both free remailers and those which charge for
usage. (And a charge on a remailer which agrees with the market probably
won't be high enough to stop a really rich junk mailer from spending the
cash on junk mailings.)

--
| Sameer Parekh-zane@genesis.MCS.COM-PFA related mail to pfa@genesis.MCS.COM |
| Apprentice Philosopher, Writer, Physicist, Healer, Programmer, Lover, more |
| "Symbiosis is Good" - Me_"Specialization is for Insects" - R. A. Heinlein_/
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