Chapter 2: The Evolution of Ciphers

Over the last several centuries, we have seen advancements in civilization, along with improvements in technology. As a result, we have seen an evolution in the methods used to conceal information. To set the foundation for more advanced topics that we will be covering in this book, we'll review some ancient techniques to conceal information. We'll start with a brief overview of some early ways to hide messages. We'll learn how data was concealed using a tool called a scytale, along with a radical method using a tattoo etched on a trusted servant's head. We'll then see how data was concealed using monoalphabetic and then polyalphabetic ciphers along with an example of each, using both the Caesar and Vigenère ciphers.

We'll then see how the effect of war led to advances in the way to encode and securely transmit messages. We'll discover how Claude Shannon, whose early research is still influential in modern...