Summary
In this chapter, we learned about some of the early uses of encryption. We saw how primitive methods such as tattoos, along with tools such as the scytale, were used to conceal information. We then took a closer look at the differences between a monoalphabetic and polyalphabetic cipher and outlined examples of both. We discovered how, throughout the centuries, military leaders sought ways to send and receive messages to their allies during times of war or conflict. Methods to send messages included using dogs, along with homing pigeons, telegraph, telephones, and radio.
Along with the advances in technology came the threat of someone intercepting the messages. As we moved into the digital age, scientist Claude Shannon helped shape the field of computing and cryptography. We learned how substitution and permutation could provide confusion and diffusion during encryption. We then learned how the Feistel cipher provides the template for most modern block ciphers. We saw how...
