NetBill is a system for micropayments for information goods on the Internet. This paper presents the NetBill protocol and describes its security and transactional features. Among our key innovations are: • An atomic certified delivery method so that a customer pays if and only if she receives her information goods intact. • Outsourcing access control: different users can use different access control servers. • A credential mechanism allowing users to prove membership in groups. This supports discounts. • A structure for constructing pseudonyms to protect the identities of consumers.

There is tremendous demand for the ability to be able to electronically buy and sell goods over networks. This field is called electronic commerce, and it has inspired a large variety of work. Unfortunately, much of that work ignores traditional transaction processing concerns — chiefly atomicity. This paper discusses the role of atomicity in electronic commerce. It then briefly surveys some major types of electronic commerce pointing out flaws in atomicity. We pay special attention to the atomicity problems of proposals for digital cash. The paper present two examples of highly atomic

Electronic commerce challenges our notions of distributed transactions in several ways. I discuss issues how distributed transactions can apply to electronic transactions, with special emphasis on the role of

What properties of money are important for electronic commerce? We argue that both transactional and privacy properties distinguish electronic commerce systems. We provide a quick overview of the history of money. We then consider privacy provided by different forms of money, and socially desirable disclosure of information as specified by legal reporting requirements. We classify electronic and traditional commerce systems into two categories: . token systems, which exchange markers representing value . notational systems, where value is stored as notations in a ledger or computer. We analyze different forms of traditional money based on the degree to which they protect the privacy and preserve transactional ACID (atomicity, consistency, isolation, durability) properties. Finally we apply our evaluation criteria to two proposed electronic commerce systems: Digicash, (Chaum, 1985; Chaum, 1992) a token-based system; and NetBill, (Sirbu, 1995) a notational system. 1 Token and Notational...

There is a tremendous demand to electronically buy and sell goods over networks. This field is called electronic commerce, and it has inspired a large variety of work. Unfortunately, much of this activity ignores traditional transaction processing concerns — chiefly atomicity. This paper discusses the role of atomicity in electronic commerce, pointing out various atomic flaws. Special attention is given to the atomicity problems of digital money proposals. Two examples of highly atomic electronic commerce systems, NetBill and cryptographic postage indicia, are presented. ELECTRONIC COMMERCE If you regularly use the World Wide Web, you have probably noticed that much of the information on it is worth what you pay for it. To improve the quality of available electronic information, we must create mechanisms to conveniently compensate the creators and owners of network information. If we want to put the Library of Congress online, we will first have to find a way to compensate copyright owners. Electronic commerce is an attempt to address such problems. The idea is to build mechanisms that make it simple to buy and sell goods online. These mechanisms have attracted significant interest. Besides enabling a new type of commerce, they appear to offer a variety of benefits, including increasing the range of information readily available to most people, 32 n W making automatic search and retrieval of that information easy, and reducing costs by simplifying or eliminating human involvement in processing and fulfilling orders. Here is one indicator of the excitement over electronic commerce: The June 12, 1995, issue of Business Week includes the following projection of the role of electronic commerce. This projection is probably overly optimistic, but it is a sign that electronic commerce is being taken seriously in some quarters.

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Executive summary For applications such as electronic voting and electronic payments, anonymity and privacy are strictly necessary. In a democratic society public elections will be held anonymously and citizens have a fundamental right to privacy, for example when buying goods or subscribing to services. However, current technologies such as databases, online connections, mobile communications, may lead to an increased erosion of privacy. For the time being no widespread communications and payment technologies are available to provide on-line shopping without giving away a substantial amount of personal information. Applications like email, publishing and web browsing are widely accepted without anonymity properties. This document describes the anonymity requirements of a variety of applications in which anonymity and privacy play an important role: (1) anonymous connections, which

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