The term cryptology is derived from the Greek kryptós, "hidden," and lógos, "word." Note that cryptology/cryptography encompasses much more than mere secrecy. Cryptographic security may result (when, and only when, well chosen algorithms and protocols are properly used); these intentions may include authentication of the participants to each other (with or without secrecy), integrity checks of messages sent (also with or without secrecy), and of course secrecy of the message sent. In most instances, secrecy obtains when legitimate users, the transmitter and the receiver, are able to transform information into a ciphertext? by use of an encryption algorithm (in all modern cases controlled by one of many possible [cryptographic key]?s) -- i.e., a piece of information which customizes the operation of the encryption algorithm. For a large class of such algorithms, the key is known to both users and must not be known by any other. Although the cipher is inscrutable and often unforgeable to anyone without this secret key, the authorized receiver can either decrypt the cipher to recover the hidden information or verify that it was sent in all likelihood by someone possessing the key.
Much is frequently confused, and misused, in discussions of cryptography. Readers are warned that there is much irresponsible and poorly informed, but authoritatively stated, information available on the subject. Terms often confused, with unfortunate consequences on understanding, are code and cipher. Even experts occasionally employ these terms as though they were synonymous.
"Crypto" is a common abbreviation for cryptology.
See also: