The advantages of the Internet as a medium for publishing information are manifold, but in many respects it defies the controls that make commerce in information (documents, pictures, etc.) commercially viable. Traditional forms of intellectual property protection cannot be easily extended to today's Internet environment, but there is a great deal of commercial motivation to develop new technology for this purpose. While most of us are familiar with privacy protection based on cryptography, intellectual property must be protected in a customer/provider relationship where copying, the most easily performed computer function, is a threat to the provider.