Everyday Cryptography: Fundamental Principles and Applications

When Bruce Schneier first published Applied Cryptography in 1994, it was a watershed event, given that is was one of the first comprehensive texts on the topic that existed outside of the military.

In the nearly 20 years since the book came out, a lot has changed in the world of encryption and cryptography.  A number of books have been written to fill that gap and Everyday Cryptography: Fundamental Principles and Applications is one of them that have recently been published.

While the title Everyday Cryptography may give the impression that this is an introductory text; that is not the case. Author Keith Martin is the director of the information security group at Royal Holloway, a division of the University of London, and the book is meant for information security professionals in addition to being used as a main reference for a principles of cryptography course. The book is also a great reference for those studying for the CISSP exam.

While the book notes that almost no prior knowledge of mathematics is required since the book deliberately avoids the details of the mathematical techniques underpinning cryptographic mechanisms.  That might be a bit of a misnomer as the book does get into the mathematics of cryptography.  While the mathematics in the book is not overwhelming, they are certainly not underwhelming.  For those that want a deeper look, the book includes an appendix for many of the mathematical concepts detailed in the book.

Two benefits of the book are that it stresses practical aspects of cryptography and real-world scenarios.  The mathematics detailed avoids number theory with a focus on practicability.  It also shows how cryptography is used as the underlying technology behind information security, rather than simply focusing on the abstracts of the potential of cryptography.

With that, the books 13 (made up of 4 parts) chapters provide a comprehensive overview of the theory and practice around all as aspects of contemporary cryptography.  Each of the chapters end with a summary, detailed lists of items for further reading, and sets of penetration questions that challenge the reader.   Readers are advised to spend time on these questions as it is often easy for the reader to feel that they understand the material. The questions can quickly humble the reader and show them that it may not be the case.

Part 1 is titled Setting the Scene and provides a comprehensive introduction to the fundamental of cryptography.  Chapter 1 (freely available here) details the basic principles about cryptography and provides a high-level introduction.

Chapter 2 provides a good overview of the history of cryptography.  It details a number of obsolete, yet historically relevant ciphers, such as the Vigenère cipher from the 1500’s, to the Playfair cipher from the mid-1800’s and others.  Martin provides a good overview of the cryptanalysis of the Vigenère cipher and lessons learned from it.

Chapters 4-9 comprise part 2, and provide a thorough overview of the various forms of encryption (symmetric and asymmetric) and digital signatures.  This section gets into some of the deeper mathematics of cryptography.  While the author states that almost no prior knowledge of mathematics is needed; those without a background will surely be confused by some of the material.

Chapter 7 closes with a good overview of the relationship between digital signatures and handwritten signatures.  The author notes the importance of resisting any temptation to consider digital signatures as a direct electronic equivalent of handwritten signatures. He then provides a detailed outline of the environmental, security, practical and flexibility differences between them.

Key management is one of the most important aspects of cryptography and often the most difficult to execute on.  Part of the difficulty around key management is at the user level, with key updates, passphrase management and more.  Ultimately, effective key management is essential to the underlying security of the cryptosystem.  The 2 chapters in part 3 provide a thorough synopsis of the fundamentals of key management.

Part 4 closes the book with two chapters on practical cryptographic applications.  Chapter 12 details how cryptography can be used on the internet, secure payment cards, video broadcasting and more.

The book concludes with an appendix on the mathematics of cryptography, which takes a look at the basic mathematical concepts the underlie some of the material in the book.

This book is not for the fainthearted and is not an introductory text on the topic. It is meant for the advanced reader or someone taking a college level course.  For such a reader serious about a significant overview of the essentials on the topic, Everyday Cryptography: Fundamental Principles and Applications is an excellent reference.

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