ABSTRACT
Cryptography is essentially the art of secret writing. To most people, this is
confined to the pages of a detective story (remember the ‘‘dancing figures’’
faced by Sherlock Holmes) or is something that is relevant in the context of
military communication. In a war, messages need to be exchanged between
units of the same army to coordinate joint maneuvers. Since such messages
can easily fall into enemy hands, it should be ensured that none but the
intended recipient can read the message. In fact, a system of exchanging
secret messages was practiced in the time of Julius Caesar, and the system is
called ‘‘Caesar shift’’ after him.
