Susan Meyer 
History of Cryptography [PDF ebook] 

The intriguing tale of cryptography stretches all the way back into ancient times and has been evolving ever since. From Julius Caesar to the modern cryptography of computers, readers will be enraptured by the stories and examples of how some of the greatest minds of history have figured out how to make and break codes. Engaging text includes samples of codes throughout the lively story of cryptography. Readers will quickly become absorbed by this fast-paced, code-cracking history chock-full of mystery and intrigue.