The Code Book by Simon Singh relates the history of cryptography, from the basics of hiding secrets which begins in ancient Greece with stenography, and then moves into the start of true cryptography with the invention of the monoalphabetic cypher. As he follows the changes in cryptography, it is not just the codes themselves he pays attention to, although he describes how each code was created and used, but also details the cryptanalyst that drove the development of new cyphers in their battle of wits. Singh tells us the origins and uses of the Vigenere cypher, and then relates how Babbage broke it and what its weaknesses are.
The story continues onto modern day, with an extended stop at Bletchly Park, a detour into the decoding of ancient languages such as ancient Egyptian. Things really begin to get interesting once one-way functions come into the story, eventually leading into a description of how the very encryption in use over the Internet to this day, asymmetric encryption, came about and how it is implemented. However, the story does not end there, pressing forward to explain how modern encryption could be broken by a quantum computer, and at the same time explaining how a system based on the same principles as the quantum computer could defeat it, with quantum encryption.
Singh finally ends the book with a look at the current political climate surrounding encryption, and encouraging the reader to contemplate whether encryption is truly the barrier to law enforcement that many claim it to be.
The Code Book makes a wonderful introduction to the world of cryptography for anyone with even a passing interest. After reading this book, I find that my interest in cryptography has grown from a small but definite interest, to one I am determined to pursue, to an extent that led me to purchase Bruce Schneier’s Applied Cryptography.
The Code Book (Amazon)