Date: Thu, 20 Oct 2005 11:31:39 -0700 From: cyphrpunk <cyphrpunk@gmail.com>
2. Cash payments are final. After the fact, the paying party has no means to reverse the payment. We call this property of cash transactions _irreversibility_.
Certainly Chaum ecash has this property. Because deposits are unlinkable to withdrawals, there is no way even in principle to reverse a transaction.
This is not strictly correct. The payer can reveal the blinding factor, making the payment traceable. I believe Chaum deliberately chose for one-way untraceability (untraceable by the payee but not by the payer) in order to address concerns such as blackmailing, extortion, etc. The protocol can be modified to make it fully untraceable, but that's not how it is designed.
3. Cash payments are _peer-to-peer_. There is no distinction between merchants and customers; anyone can pay anyone. In particular, anybody can receive cash payments without contracts with third parties.
Again this is precisely how Chaum ecash works. Everyone can receive ecash and everyone can spend it. There is no distinction between buyers and vendors. Of course, transactions do need the aid of the issuer, but that is true of all online payment systems including Daniel's.
Apart from the transferability issue, I think there are some systems that do not rely on an issuer at all (in effect any payee is an issuer). Manasse's Millicent comes to mind, but I confess that I don't fully remember the details. Ray