The New Dictionary of Cultural Literacy, Third Edition. 2002.
cryptography
The science of coding and decoding messages so as to keep these messages secure. Coding (seeencryption) takes place using a key that ideally is known only by the sender and intended recipient of the message.
Historically used in warfare, cryptography is now used routinely in computer networks. This often pits the desire of individuals and businesses to keep Internet information private against the need of government to investigate crime and terrorism.