Elementary Information Security, 3rd Edition

▶ 7.3 Computer-Based Encryption

Modern, computer-based encryption algorithms are far more complicated than the older mechanical or hand-operated ciphers. Their sophisticated design and operation foils traditional known-plaintext and known-ciphertext attacks. In general, the only practical attack is to try to guess the key through trial and error. This is the same as trial-and-error attacks on passwords, except that we try harder to avoid biases in key selection. A realistic, general-purpose trial-and-error attack must examine a crypto key’s entire search space.

The Data Encryption Standard

In 1975, the U.S. government unveiled the algorithm that became the Data Encryption Standard, commonly called DES. The algorithm was quickly ...