The Basics

There has always been a need for secrecy. Whether vital wartime military information, a bank transaction, or a letter to a friend, governments, organizations, and individuals have always been and always will be concerned with keeping their secret and transmitting private information securely. Hence, the science known today as cryptology was developed. Cryptology encompasses two opposite yet related disciplines: cryptography and cryptanalysis. The word cryptography is derived from the Greek words krypto (secret) and graphos (writing) [4, p. 13] and refers to the aspect of cryptology concerned with enciphering, or disguising, a message in such a way that only the sender and the intended recipient can decipher it. Cryptanalysis is the enemy of cryptography in cryptanalysis is the science of deciphering the enciphered message without the key and without the consent of the sender or the receiver [1, p. 2]. It is important that we understand that cryptology is a science of ciphers and not codes. The difference between a code and a cipher is that in a cipher each letter of the original message is replaced with a different and distinct letter or symbol, or rearranged in such a way that it is unintelligible [ 4, p. 33]. A code replaces entire words or phrases with other words or phrases having a secret meaning. In order to understand a code, the recipient must have access to a cod