To understand public-key cryptography fully, one must first understand the essentials of one of the basic tools in contemporary cryptology: secret-sharing. There is only one way to design systems whose overall reliability must be greater than that of some critical components—as is the case for aircraft, nuclear weapons, and communications systems—and that is by the appropriate use of redundancy so the system can continue to function even though some components fail. The same is true for information-based systems in which the probability of the security functions being realized must be greater than the probability that some of the participants will ...(100 of 15098 words)