Fundamentals of Information Systems Security, 4th Edition

What Is Cryptography?

Cryptography is the art of transforming a readable message into a form that is readable only by authorized users; it is described as follows:

• Unencrypted information—Information in understandable form, which is called plaintext, or cleartext

• Encrypted information—Information in scrambled form, which is called ciphertext

Encryption is the process of scrambling plaintext into ciphertext, and decryption is the opposite process (i.e., unscrambling ciphertext into plaintext). For decryption to work properly, the decrypted plaintext must be the same as the original plaintext before encryption.

Traditional encryption and decryption use known mathematical processes, called algorithms (i.e., repeatable processes that produce ...