From secret decoder rings to government policy statements, the challenges of hiding and discovering information within other information have long compelled the intellect. Cryptology is a fascinating subject with which almost every schoolchild has some hands-on familiarity. And yet, for good reasons, it is a discipline that throughout time has been shrouded in the deepest levels of secrecy and used by governments to protect their most sensitive weapons. Cryptography’s role in military and diplomatic affairs has always been deadly serious. It is no exaggeration to declare that successes and failures of cryptography have shaped the outcome of wars and the course of history; nor is it an exaggeration to state that the successes and failures of cryptography are setting our current course of history.
Consider the American Civil war battle of Antietam in September of 1862, when George McClellan commanded the Union forces against Robert E. Lee’s Confederate forces near Sharpsburg, Maryland. A few days earlier, two Union soldiers had found a piece of paper near their camp, which turned out to be a copy of an order issued by Lee detailing his plans for the invasion of Maryland. The order had not been encrypted. With the information it contained, McClellan precisely knew the location of the commands of Lee’s scattered army and was able to destroy Lee’s army before they reunited.