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Introduction to Cryptography

Hans Delfs and Helmut Knebl
Publication Date: 
Number of Pages: 
Information Security and Cryptography
[Reviewed by
Allen Stenger
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This is a thorough introductory text on cryptography from an engineering viewpoint. It provides a good overview of the whole subject, including secret-key (“symmetric”) and public-key methods, hash functions, and signing. There’s a 90-page appendix that summarizes the mathematics needed (mostly number theory, with some abstract algebra and probability). The book is well-written and easy to follow.

I like the organization of this book. The first half is the “how-to” part, and explains the steps of all the commonly-used encryption algorithms and also has a lot on how they have been attacked and ways to avoid successful attacks. This section also covers many recent applications such as electronic voting and digital cash. It only covers systems that are still used in practice and omits historically-important systems such as the Enigma.

The second half of the book is the “why” part, that has all the theorems and proofs and deals with what can be proved about these algorithms. It is organized by the property being studied rather than by algorithm. This part is a great deal more difficult and advanced than the first part.

The exercises are reasonable, with a mixture of examples to work out and things to prove. There are only about a dozen exercises per chapter, so most courses would need to add their own exercises.

A more purely-mathematical book is Hoffstein & Pipher & Silverman’s An Introduction to Mathematical Cryptography. This is well-regarded but does not have the same breadth as the present book, and concentrates on public-key methods. A more engineering-oriented book is Schneier’s Applied Cryptography (Wiley, 2015). This suffers from being old (it is a slightly-revised version of the 1996 edition) but it is good for what it covers.

Allen Stenger is a math hobbyist and retired software developer. He is an editor of the Missouri Journal of Mathematical Sciences. His mathematical interests are number theory and classical analysis.

See the table of contents in the publisher's webpage.