Block Ciphers
Niels Ferguson, Bruce Schneier, Tadayoshi Kohno · 2015
Block ciphers are one of the fundamental building blocks for cryptographic systems. There is a lot of literature on block ciphers, and they are among the best-understood parts of cryptography. This chapter provides a firmer understanding of block ciphers: what they are, how cryptographers view them, and how to choose between different options. A block cipher is an encryption function for fixed-size blocks of data. Related-key attack and esoteric attack types are some types of attacks discussed in this chapter. In practice, parity attacks have more effect on the formal definition of security than on real-world systems. The real block cipher never generates an odd permutation. Virtually all block ciphers consist of several repetitions of a weak block cipher, known as a round. The Data Encryption Standard (DES) now survives in the form of 3DES and Advanced Encryption Standard (AES) is the U.S. government standard created to replace DES.