Simply encryption uses a mathematical algorithm to scramble
a message to create the cipher text. A key is used by the
algorithm to determine the scramble pattern. The same key can then be used to
unscramble or decipher the message. While this isn’t a perfect analogy, a
deadbolt on a door is nothing more than a chunk of metal until someone inserts a
key that can manipulate the tumblers and advance the bolt. The lock and the door
are then secure until the correct key is used to reverse the process. Like the
door analogy, more than one person might have the key but, without the correct
key, the lock won’t budge. Also, somewhat like the door analogy, cipher text
might require multiple keys both to lock and unlock. Figure 9-14 shows a common,
simplified view of encryption.
Figure 9-14: Cleartext
being processed using a key to produce cipher text
The key terms in the process include data, key, encryption
algorithm, and cipher text.