Symmetric-key cryptography

Abstract

In this chapter, we give an introduction to basic methods of symmetric-key cryptography. At first, we consider symmetric-key encryption.We explain the notions of stream and block ciphers. The operation modes of block ciphers are studied and, as prominent examples for block ciphers, DES and AES are described. Later, we introduce cryptographic hash functions. Methods for the construction of cryptographic hash functions, such as Merkle–Damg˚ard’s method and the sponge construction, are explained in detail. As an application of hash functions, we get message authentication codes, MACs for short. MACs are the standard symmetric-key technique to guarantee the integrity and authenticity of messages.