Chaum establishes a procedure for engaging in transactions with organizations that protect the privacy of the individual and yet allow the necessary transfer of information. He makes two initial assumptions and then relaxes them later for further usage of the system. First, each individual is allowed at most one relationship per organization. Second, only a particular organization has the power to create pseudonyms or to issue credentials.
In the first part of the paper, the author presents the basic system via analogy, then he gives the actual system using digital signatures. The second section details how pseudonyms are authorized and relaxes the second assumption. Section 3 relaxes the first assumption and illustrates the results with applications. Section 4 discusses transforming and combining credentials. The paper concludes with Section 5, describing how users can maintain exclusive control over the database of their own relationships. The heart of the paper is the use of data encryption methods to develop a system that protects privacy and maintains security but allows individuals to enjoy the benefits of sharing information.
The tool used is classical mathematics--modular arithmetic and group theory. He uses these classical methods skillfully to present a method that appears to be remarkably original, innovative, and effective. The section on validators, that is, “persons establishing pseudonyms with organizations by means of signatures,” is well done and creative.
The paper as I received it contains no reading list or documentation of the survey of the literature. Although the author lists sources of research by citation number, I did not have the bibliography of citations at the end of the paper. I found that uncomfortable. Perhaps the list was contained somewhere else in the proceedings, which I did not receive.
The paper is well written. If one is interested in data encryption methods, privacy and security of documents, or the mathematics of setting up such a system, this paper will be most interesting.
