Cryptology and Cryptography

CIPHERTEXT: The encrypted form of the PLAINTEXT.

CODE: An unvarying rule for replacing a piece of information with another object, not necessarily of the same sort e.g. ASCII.

CRYPTANALYSIS: The science (and art) of recovering information from ciphers without knowledge of the key.

CRYPTOGRAPHY: The science of the enciphering and deciphering of messages in secret code or cipher.

CRYPTOSYSTEM: A system for encrypting information.

DECRYPTION: The process of converting the CIPHER back into PLAINTEXT.

ENCRYPTION: The process of converting the PLAINTEXT into a CIPHER.

KEY: The secret information known only to the transmitter and the receiver which is used to secure the PLAINTEXT.

MONOALPHABETIC SUBSTITUTION: A method of encryption where a letter in the plaintext is always replaced by the same letter in the ciphertext.

PLAINTEXT: The source information to be secured.

POLYALPHABETIC SUBSTITUTION: A method of encryption where a letter in the plaintext is not always replaced by the same letter in the ciphertext.