In 1917, Gilbert S. Vernam, an AT&T employee, invented a polyalphabetic cipher machine that used a non-repeating random key.

The most popular modern version of steganography involves hiding information within files that contain digital pictures or other images.

Standard-HTTP (S-HTTP) is an extended version of the Hypertext Transfer Protocol that provides for the encryption of individual messages between a client and server across the Internet.

____ is the amount of effort (usually in hours) required to perform cryptanalysis on an encoded message so that it may be decrypted when the key or algorithm (or both) are unknown.

Julius Caesar was associated with an early version of the transposition cipher.

DES uses a 64-bit key.

Sequence encryption is a series of encryptions and decryptions between a number of systems, wherein each system in a network decrypts the message sent to it and then reencrypts it using different keys and sends it to the next neighbor, and this process continues until the message reaches the final destination.

Two hundred and eighty five computers can crack a 56-bit key in one year, ten times as many would do it in a little over a month.

A method of encryption that requires the same secret key to encipher and decipher the message is known as ____ encryption.

One encryption method made popular by spy movies involves using the text in a book as the key to decrypt a message.