Not only does this book explain in accessible terms the notions involved in public-key cryptography, it also addresses the weaknesses of the various systems extant, and describes a number of (often special case) cryptanalytic attacks.

The book has six major sections: an introduction to classical cryptography; an introduction to the notion of public-key systems; a chapter on knapsack systems; a chapter on RSA; a chapter on other bases for cryptosystems; and a chapter on cryptographic protocols that includes some of the byways of asymmetric cryptography as well as the number theoretic approach to problems such as zero-knowledge proofs, selective sharing of secrets, and coin flipping by telephone. The knapsack and RSA chapters each have significant sections on how to attack the systems they cover.

The book is not for the mathematically fainthearted. It emphasizes the mathematics of the various public-key ciphers and the cryptanalytic attacks described, rather than the application of public-key systems for all of the variants of user identification and authentication applications that have been identified. It requires either an extensive background in number theory or the time to master some of the techniques used (including GCD and “fast” exponentiation) and the ability to use them. To this end, one of the appendices is entitled “A Tutorial in Number Theory.” This appendix will help the reader understand the text.

It is possible to use the book for self-study, although it would be prudent to have a colleague accessible who understands the deeper number theory when and if you need it. You will need to have algorithms for finding the GCD and so on at hand if you are planning to work the examples. The appendix giving the tutorial on number theory contains descriptions of the key algorithms in mathematical notation. I find the algorithms in Denning [1] more useful for working the examples, however. Working the examples is the best way to comprehend all of the nuances of the methods described. The book is replete with examples, which are clearly presented and carefully explained. Although problems are not provided with each chapter, an appendix contains 100 problems drawn from the material in the book.

As indicated above, the book presumes some mathematical sophistication to deal with the subject. Even so, it is well written and could be attacked by any interested individual. It is especially valuable because it integrates the cryptanalytic approaches for the various public key methods with the explanatory development of the methods themselves.

I recommend the book highly as an addition to the library of any security engineer or scientist interested in security issues. Security engineers need a grasp of the results presented in the book in order to place the role of public key cryptosystems in perspective.