14.6 Summary
In this chapter, we learned what block ciphers are (encryption functions mapping plaintext blocks of fixed size b onto ciphertext blocks of the same size b), what design principles are used to construct block ciphers (confusion and diffusion), and what theoretical constructions are used to model block ciphers (pseudorandom permutations).
Moreover, we covered iterated block ciphers and substitution-permutation networks, the two major paradigms for designing secure block ciphers. We then studied in detail how AES, the block cipher chosen as a result of a world-wide call for algorithms by the US standardization body NIST, works. Finally, we highlighted the most common modes of operation of block ciphers, including their working principle, advantages, and disadvantages.
In the next chapter, we will take a detailed look at one more mode of operation. It is called Authenticated Encryption with Additional Data (AEAD) and plays a crucial role in TLS 1.3. In contrast to the other...
