Information theory and privacy in data banks

The problem of providing privacy and security in retrieval systems falls into two rather modern disciplines: information theory and computer science. In this paper the concern is primarily with the former, i.e., how to relate security of data records in computerized retrieval systems and data banks with Shannon's information-theoretic treatment of secrecy systems for natural language messages in communication systems. In doing so, it is useful to establish first the analogy between retrieval systems and certain communication channels.