Design, implementation, and deployment of the iKP secure electronic payment system

This paper discusses the design, implementation, and deployment of a secure and practical payment system for electronic commerce on the Internet. The system is based on the iKP family of protocols - (i = 1, 2, 3) - developed at IBM Research. The protocols implement credit card-based transactions between buyers and merchants while the existing financial network is used for payment clearing and authorization. The protocols are extensible and can be readily applied to other account-based payment models, such as debit cards. They are based on careful and minimal use of public-key cryptography, and can be implemented in either software or hardware. Individual protocols differ in both complexity and degree of security. In addition to being both a precursor and a direct ancestor of the well-known SET standard, iKP-based payment systems have been in continuous operation on the Internet since mid-1996. This longevity - as well as the security, and relative simplicity, of the underlying mechanisms - makes the iKP experience unique. For this reason, this paper also reports on, and addresses, a number of practical issues arising in the course of implementation and real-world deployment of a secure payment system.