Safeguarding digital library contents: Charging for online content

Charging for content is critical to the financial viability of many digital libraries as well as other (e.g. direct) providers of online content. Currently, there are a substantial number of different charging mechanisms available or proposed. We investigate the need for charging mechanisms, in particular for micropayments - charging for small amounts. We discuss the requirements for successful charging mechanisms. We briefly describe two credit card charging mechanisms - using the SSL protocol (which is most common today) and the SET standard for charge card payments. We also describe the MiniPay micropayment mechanism for charging small amounts 'per click', and compare it to other micropayment mechanisms proposed. A bias is acknowledged for SET and MiniPay; the author was among the developers of both, and both are being produced by IBM.