Background Theory

The word ‘cryptography’ is derived from the greek words kryptos, which means hidden and graphia which means writing. Cryptography is the art of keeping secret the contents of a message transmitted over an unsecured communication channel. For example, the sender encrypts a message and thus, transforms its contents into an unintelligible form. The encrypted message or ciphertext is then transmitted over an unsecured channel. The receiver must decrypt the ciphertext to obtain the original message by performing an inverse transformation. The secrecy and security of the system relies on only the recipient having knowledge of the decryption transformation.