I agree with Anonymous that there are problems with the actual use of digital cash in the near term. But it depends to some extent on what problem you are trying to solve. One concern I have is that the move to electronic payments will decrease personal privacy by making it easier to log and record transactions. Dossiers could be built up which would track the spending patterns of each of us. Already, when I order something over the phone or electronically using my Visa card, a record is kept of exactly how much I spent and where I spent it. As time goes on, more transactions may be done in this way, and the net result could be a great loss of privacy. Paying in cash is still possible through the mail, but it is insecure and inconvenient. I think that the convenience of credit and debit cards will overcome most people's privacy concerns and that we will find ourselves in a situation where great volumes of information exist about people's private lives. This is a place that I could see digital cash playing a role. Imagine a Visa-like system in which I am not anonymous to the bank. In this model, imagine that the bank is granting me credit similar to a credit card. But instead of giving me just an account number which I read over the phone or send in an email message, it gives me the right to request digital cash on demand. I keep some digital cash around and spend it for transactions as I described in my previous posts. When I get low I send some email to the bank and get some more dcash. Every month I send a check to the bank to cover my account just as I do with my credit cards. My relations with the bank are very similar to my current relationships with the credit card companies: frequent withdrawals and a single payment each month by check. This has several advantages over the system which we are heading towards. No records are kept of where I spend my money. All the bank knows is how much I have withdrawn each month; I may or may not have spent it at that time. For some transactions (e.g. software) I could be anonymous to the vendor; for others the vendor might know my real address, but still no central location is able to track everything I buy. (There is also a security advantage over the ridiculous current system in which knowing a 16 digit number and an expiration date allows anyone to order anything in my name!) Furthermore, I don't see why this system could not be as legal as current credit cards. All that really differs in this system is the inability to track where users spend their money, and as far as I know this ability was never an important legal aspect of credit cards. Certainly nobody will admit today that the government has a vested interest in moving towards an environment in which every financial transaction is tracked. Granted, this does not provide full anonymity. It is still possible to see roughly how much each person spends (although nothing stops a person from withdrawing much more cash than he will spend in a given month, except per- haps for interest expenses; but maybe he can lend the extra digicash itself and gain interest on that to compensate). And it is oriented around the same customer/vendor model that Anonymous criticized. But I maintain that this model represents the majority of electronic transactions, today and in the near future. It's worth noting that it is not trivial to become a merchant who can accept credit cards. I went through this with a business I had a couple of years ago. We were selling software through mail order, and this makes the credit card companies very nervous. There is so much phone fraud in which credit card numbers are accumulated over a few months, then large amounts of charges made against them. By the time the user receives his monthly statement and complains, the vendor has disappeared. In order to get our credit card terminal we went to a company which "helps" startups with this. They seemed like a pretty shady outfit, themselves. We had to fudge our application to say that we'd be selling something like 50% of the units at trade shows, which apparently counted as over-the-counter sales. And we had to pay about $3,000 up front, as a bribe, it seemed. Even then we probably couldn't have done it if we hadn't had an office in the business district. Under the digital cash system, this might be less of a problem. The main problem with digital cash is double-spending, and if you are willing to go with online verification (reasonable for any business which is going to take anything over several hours to deliver the merchandise) this can be completely prevented. So there is no longer any possibility of merchants collecting credit card numbers for later fraud. (You still have problems with non-delivery of merchandise, though, so not all risks are eliminated.) This might eventually make the system more widely available than current credit cards. I don't know whether this system could be used to support illegal actions, tax evasion, gambling, or whatever. That is not the purpose of this proposal. It does offer the prospect of improving personal privacy and security, in a framework that might even be legal, and that's not bad. Hal Finney hfinney@shell.portal.com