# Questions tagged [shift-register]

Shift registers are at the heart of cryptography and error-correction. In cryptography they are the main tool for generating long pseudorandom binary sequences which can be used as keys for two communicating parties in symmetric cryptography. Practically all military cryptography makes use of them.

11 questions
Filter by
Sorted by
Tagged with
74 views

### Question about obtaining a keystream from a linear-feedback shift register

For a homework question we are obtaining a keystream from a LFSR and I am slightly confused on which digits are used as the key. For example I have this table here, ...
• 101
1 vote
118 views

### How to build a lsfr based on sequence $s_i = s_{i-1} + s_{i-4}$? [closed]

How do I know where my XOR gates go? What does the F2 stand for here? Also the next task is to generate the sequence (with initialisation vector $s_0 = 1, s_1 = s_2 = s_3 = 0$) until it becomes ...
1 vote
Let $\omega$ denote the set of non-negative integers. For $n\in\omega\setminus\{0\}$ define the rotation function $$\text{rot}_n:\{0,1\}^n \to \{0,1\}^n$$ by $x \mapsto x'$ where $x'_k = x_{k+1}$ ...