Preface to Cryptography Engineering

Most books cover what cryptography is—what current cryptographic designs are and how existing cryptographic protocols, like SSL/TLS, work. Bruce Schneier's earlier book, Applied Cryptography, is like this. Such books serve as invaluable references for anyone working with cryptography. But such books are also one step removed from the needs of cryptography and security engineers in practice. Cryptography and security engineers need to know more than how current cryptographic protocols work; they need to know how to use cryptography.

To know how to use cryptography, one must learn to think like a cryptographer. This book is designed to help you achieve that goal. We do this through immersion. Rather than broadly discuss all the protocols one might encounter in cryptography, we dive deeply into the design and analysis of specific, concrete protocols. We walk you—hand-in-hand—through how we go about designing cryptographic protocols. We share with you the reasons we make certain design decisions over others, and point out potential pitfalls along the way.

By learning how to think like a cryptographer, you will also learn how to be a more intelligent user of cryptography. You will be able to look at existing cryptography toolkits, understand their core functionality, and know how to use them. You will also better understand the challenges involved with cryptography, and how to think about and overcome those challenges.

This book also serves as a gateway to learning about computer security. Computer security is, in many ways, a superset of cryptography. Both computer security and cryptography are about designing and evaluating objects (systems or algorithms) intended to behave in certain ways even in the presence of an adversary. In this book, you will learn how to think about the adversary in the context of cryptography. Once you know how to think like adversaries, you can apply that mindset to the security of computer systems in general.