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What Is Cryptology?
| Good [+1]Toggle ReplyLink» Nuclear replied on Thu Jul 11, 2002 @ 1:44am |
 Coolness: 2604185 | What is cryptology? Cryptography? Plaintext? Ciphertext? Encryption? Key?
The story begins: When Julius Caesar sent messages to his trusted acquaintances, he didn't trust the messengers. So he replaced every A by a D, every B by a E, and so on through the alphabet. Only someone who knew the ``shift by 3'' rule could decipher his messages. A cryptosystem or cipher system is a method of disguising messages so that only certain people can see through the disguise. Cryptography is the art of creating and using cryptosystems. Cryptanalysis is the art of breaking cryptosystems---seeing through the disguise even when you're not supposed to be able to. Cryptology is the study of both cryptography and cryptanalysis. The original message is called a plaintext. The disguised message is called a ciphertext. Encryption means any procedure to convert plaintext into ciphertext. Decryption means any procedure to convert ciphertext into plaintext. A cryptosystem is usually a whole collection of algorithms. The algorithms are labelled; the labels are called keys. For instance, Caesar probably used ``shift by n'' encryption for several different values of n. It's natural to say that n is the key here. The people who are supposed to be able to see through the disguise are called recipients. Other people are enemies, opponents, interlopers, eavesdroppers, or third parties. |
What Is Cryptology?
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