Substitution-permutation networks and Feistel networks – Block Ciphers and Their Modes of Operation

• Kevanna Brown
• 01/31/202208/31/2024
• 0

14.2.5 Substitution-permutation networks and Feistel networks Modern block ciphers are often constructed as iterated functions, where a so-called round function fk : {0,1}b →{0,1}b is repeatedly applied on the plaintext m, with varying round keys k1,k2,…,kr. More formally, we can write this process as or even where ○ stands for the composition of functions. Figure…