On Thu, Oct 20, 2005 at 07:34:34PM -0400, R.A. Hettinga wrote: > At 12:32 AM +0200 10/21/05, Daniel A. Nagy wrote: > >Could you give us a reference to this one, please? > > Google is your friend, dude. > > Before making unitary global claims like you just did, you might consider > consulting the literature. It's out there.
With all due respect, this was unnecessarily rude, unfair and unwarranted. Silvio Micali is a very prolific author and he published more than one paper on more than one exchange protocol. I am actually familiar with some of his work on the subject. I was, however, specifically interested in which particular one did you have in mind. I can think of several exchange protocols that would do the job, though I don't particularly like them, because the infrastructure for carrying them out is not in place and they require more communication than is strictly necessary for obtaining a receipt. In general, I think that one should be very careful with piling up cryptographic operations and additional back-and-forth communication steps in a payment protocol, because it may easily render it unpractical. There are reasons why there are no cash-like digital payment systems, and it's not for the lack of trying (you know that better than anybody else in the world, I guess) or the lack of demand. Making it sufficiently simple is one of the most difficult challenges. -- Daniel