The need for communications confidentiality has existed since humans developed language. Accounts of the Greco-Persian wars in fifth century B.C. described steganography, (hiding the existence of a message). Cryptography, on the other hand, hides a message’s meaning. The cryptographic task of encryption enables a sender to “scramble” a message’s content, rendering it unreadable to anyone lacking the “key” to unscramble it.
Encryption, in its basic form, includes a procedure (algorithm) for scrambling the message, and a key, or specific parameters, for applying the procedure. A fundamental tenet of secure encryption is that . . .