From the Roman empire's Caesar cipher to the WWII Enigma machine, secret messages have influenced the course of history. Today, Secret Key cryptography is the backbone of all modern computing infrastructure. Properly designed, these algorithms are efficient and practical. Some are actually unbreakable, even using supercomputers or quantum technology! Secret Key Cryptography teaches you how to create Secret Key ciphers, ranging from simple pen-and-paper methods to advanced techniques used in modern computer-based cryptography. It reveals both historic examples and current innovations. You'll learn how to efficiently encrypt large files with fast stream ciphers, discover alternatives to AES encryption, and avoid strong-looking but weak ciphers. Simple language and fun-to-solve mini-ciphers make learning serious concepts easy and engaging. What's Inside, Construct 30 unbreakable ciphers, Measure the strength of your ciphers and guarantee their security, Add an undetectable backdoor to a cipher, Defeat hypothetical ultracomputers of the future, For professional engineers, computer scientists, and cryptography hobbyists. No advanced math knowledge is required. Book jacket.