## Security in Communications and Storage

Module Number: EI71060

Duration: 1 Semester

Occurence: Winter Semester

Language: English

## Staff

Professor in charge: Antonia Wachter-Zeh

## Description of achievement and assessment methods:

In a final written exam about the content of the lecture, the students should demonstrate their understanding of the considered security schemes and the respective applications. They have to show (while using only one handwritten sheet of notes) that they can evaluate and design the respective security and coding schemes for the considered applications (post-quantum cryptography, authentication, distributed data storage, private information retrieval).

## (Recommended) Requirements

Mathematical basics (in particular linear algebra)

Recommended: some knowledge in channel coding or information theory (the lectures can be taken in parallel to this lecture)

## Contents

- Motivation and practical need for secure systems

- Short overview of classical cryptography: symmetric and public

-key cryptography

- Short introduction to linear error

-correcting codes: generator and parity

-check matrix, dual code, minimum distance, MDS codes

- Post-quantum cryptography: threat of a quantum computer, code-based cryptography (McEliece & Niederreiter schemes, attacks), lattice-based cryptography

- Authentication

- Distributed data storage: choice of parameters, regenerating codes, locally repairable codes, bounds

- Basics of information theory: entropy, mutual information

- Secure distributed data storage

- Private information retrieval: basic idea (security vs anonymity vs privacy as concepts), toy schemes for 1-3 servers; computational vs. information-theoretic PIR; review of communication complexity results

- Private information retrieval over coded databases: PIR rate and capacity results

## Study goals

At the end of the course, the students are able to

- to name and explain means to achieve security in modern communication and storage systems,

- to understand and analyze basic cryptographic schemes,

- to understand the challenges of post-quantum cryptography and to name which schemes are post-quantum secure,

- for code-based cryptography: to choose a suitable error-correcting code, adapt its parameters, evaluate it, and implement it in software,

- to understand and implement known attacks on code-based cryptographic schemes,

- to give an overview of symmetric cryptography and authentication,

- to explain the main coding methods used for distributed storage systems (DSSs),

- identify various design challenges and interplay between design parameters,

- identify security issues in DSSs,

- to understand the basic principle and different forms of private information retrieval (PIR),

- give an overview of known results related to complexity, capacity, and coding methods used for PIR

## Teaching and learning methods

Lecture: The fundamental theoretical contents are presented in the lecture (by a slide presentation and on the black board) and illustrated with examples. Students are encouraged to ask questions and discuss the topics of the lecture. In an accompanying tutorial, the content of the lecture is applied by calculating problems and programming small tasks.

## Media formats

Slides and black board.

## Literature

The slides will be provided. If necessary, current research papers to each of the topics are uploaded.