the study of both cryptography and cryptanalysis. . Cryptology is derived from the Greek kryptós, "hidden," and lógos, "word." Security is given to users through a secret common key (a piece of information known only to them). The sender and the receiver of a message are able to transform information into a cipher and back to the original plain text message by virtue of this key. Although the cipher prevents anyone without this secret key from reading the message, the authorized receiver can decrypt the cipher to recover the hidden information and/or verify that it was sent by someone possessing the key.
Cryptology is an umbrella term for cryptography and cryptanalysis. Cryptology is usually taken to mean the study of mathematical, linguistic, and other coding patterns and histories. "Cryptography" is used in many English language publications in the field, as an equivalent 'highest order' term for the entire field.