R. Hirschfeld wrote:
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.
Huh - first I've heard of that, would be encouraging if that worked. How does it handle an intermediary fall guy? Say Bad Guy Bob extorts Alice, and organises the payoff to Freddy Fall Guy. This would mean that Alice can strip her blinding factors and reveal that she paid to Freddy, but as Freddy is not to be found, he can't be encouraged to reveal his blinding factors so as to reveal that Bob bolted with the dosh. iang