# Permutation and modes of operation

I'm reading the book "Serious Cryptography A Practical Introduction to Modern Encryption" from Jean-Philippe Aumasson, and in the first chapter, it is written this :

We can try to abstract out the workings of a cipher, first by identifying its two main components: a permutation and a mode of operation. A permutation is a function that transforms an item (in cryptography, a letter or a group of bits) such that each item has a unique inverse (for example, the Caesar cipher’s three-letter shift). A mode of operation is an algorithm that uses a permutation to process messages of arbitrary size.

But when I search about "mode of operation", I only found "block ciphers" using it.

Do all ciphers (for instance stream ciphers) have modes of operation?

And do all ciphers use permutation?

Thanks !

if a cipher operates on fixed length blocks it has to be a permutation by definition since a one to one function is automatically a permutation on the finite domain $$\{0,1\}^n.$$
Permutations play a significant role in asymmetric ciphers as well, and the discrete log map over the multiplicative group $$Z_{p}^{\ast}$$, for example, is a permutation.