Re: Still more on the Digicash protocol

[Hal <hfinney@shell.portal.com>]

From: Mark Twain Ecash Support <support@marktwain.com>
> Let us contemplate in which type of situation the payee will send such a
> wildcard coin. To pay a shop via TCP? No. The payment request comes in with
> the shop ID. The resulting payment won't be done with a wildcard coin.
> 
> So when will the user pay with a wildcard coin? To make a payment to a party
> that is (pseudo-) anonymous to the payor. That is, if the payor sends the
> payment via anonymous remailer, in which case the messages should be
> encrypted anyway.

There might be some situations where it is useful to send a wildcard
coin even via a TCP connection.  For example, a pseudonymous server
might pop up at some internet address different from its real one, make
some transactions, and then go away.  Or someone might set up an
anonymous account at some public server (like c2.org) and conduct
business anonymously on an ongoing basis.  In either case the payee
would be anonymous to the payor even though they communicated via TCP.
The shop would have to send its payment request using "@" as the
shop_accID field (I have heard of an undocumented "-X <payee>" switch
in the Unix ecash program which allows the shop software to control
this field in the payment request).

We have also discussed the "pipe-net" which would allow anonymous TCP
connections.  This does not look like it can be as secure as the remailer
net but for occasional or short-term use it can provide considerable
privacy protection.

I am glad that DigiCash supports this type of cash which anyone can
deposit.  Actually, I am surprised and puzzled that it does, given
Chaum's apparent reluctance to endorse schemes to allow payee anonymity
(due to political problems, apparently).  It would be interesting to hear
how DigiCash envisions this feature being used, and whether they plan to
continue to allow it.  Since it is not well documented (if at all) it's
possible that they don't plan to keep it.

But if they do, I think it would be good to adapt the protocols so this
feature is usable over TCP connections.

Hal