Cryptography

Nearly two thousand years ago, Julius Caesar sent hand written orders for an attack to several of his legions. The messages were hand carried by runner. One of the runners was subsequently captured but the enemy could not make any use of the message because they could not understand it. The enemy soldiers encouraged the runner to explain the meaning of the message, however he did not know its contents and subsequently died at the hands of his captors. All Caesar had done was transpose each letter in the message by a predetermined number of places and the message was therefore unintelligible. Caesar won a great victory that day and the era of encoded messages was born. Historically, this would appear to be the first use of codes on the battlefield and the process became known as the Caesar Code. It was only a matter of time however before all armies were using codes and the emphasis was then placed on code breaking.

Transposition codes of Caesar's type were used for more than two thousand years and became more sophisticated as time progressed but it has only been since the start of WW11 that machines have been used for encoding and encryption. Today, every developed country in the world uses a combination of encoding and encryption to protect sensitive information. It was not until the early 1970s however that civilian businesses began using encryption – up until then, it had been the sole purview of the military.

These days, we can buy encryption software for use on our own PCs to encrypt email to our friends or business colleagues, and large business houses such as the banks routinely use encryption to secure transaction details. The quality of the protection provided by encryption varies widely and is largely dependent on the type of encryption algorithm used as well as the length of the encryption key.