Applied Cryptography

by Dan Boneh, Victor Shoup

Cryptography is an indispensable tool used to protect information in computer systems. It is used everywhere and by billions of people around the world on a daily basis. It is used to protect data at rest and in motion. Cryptographic systems are an integral part of standard protocols, especially the Transport Layer Security (TLS) protocol, which makes it relatively easy to incorporate strong encryption into a wide range of applications. While extremely useful, crypto is also very fragile. The most secure cryptographic system can be made completely insecure by a single specification or programming error. No amount of unit testing will reveal a security vulnerability in a cryptosystem. Instead, to argue that a cryptosystem is secure, we rely on mathematical models and tests to show that a particular system satisfies the security properties attributed to it. We often need to introduce certain plausible assumptions to drive our security arguments. This book is about exactly building practical cryptosystems for which we can argue for security under plausible assumptions. The book covers many constructs for different tasks in cryptography. For each task we define a precise safety objective that we intend to achieve and then present constructions that achieve the required objective. To analyze the constructs, we developed a unified framework for performing cryptographic tests. A reader who has mastered this framework will be able to apply it to new constructions that may not be covered in the book.Throughout the book, we present many case studies to examine how the systems in place work. We describe common mistakes to avoid, as well as attacks on real-world systems that illustrate the importance of rigor in cryptography. We end each chapter with a fun app that applies the ideas of the chapter in an unexpected way.

2144 pages, Kindle Edition

Published October 3, 2021