Cryptography and Information Theory

Go to Course: https://www.coursera.org/learn/crypto-info-theory

Introduction

**Course Review: Cryptography and Information Theory on Coursera** In today's digital age, the security of information is more crucial than ever. As such, the need for individuals who understand the complexities of cryptography and the principles of information theory is growing rapidly. Among the various courses available, the **"Cryptography and Information Theory"** course on Coursera stands out as a comprehensive introduction to these essential topics. ### Course Overview This course offers a unique blend of cryptographic techniques and information theory, focusing on how these disciplines intersect to protect data. It dives deep into the theoretical foundations that drive secure communications, offering students essential knowledge about both practical and theoretical perspectives of security. ### Course Structure The course is structured into four main modules, each examining different aspects of cryptography and information theory: 1. **Cryptography Overview**: This introductory module sets the stage by defining crucial terminology and concepts in the field of cryptography. The course introduces key figures like Alice, Bob, and Eve, navigating through the landscape of cryptographic protection while highlighting Kerckhoff's Principle, which asserts that security should rely on the secrecy of the key, not the algorithm. The introductory discussions also address the limitations of Security by Obscurity, providing students a firm foundational understanding. 2. **Information Entropy**: Delving into the mathematical side of information theory, this module explores the concept of entropy as a measure of randomness and unpredictability. Learners will discover how entropy relates to the strength of cryptographic keys and overall security against unauthorized access. This segment effectively aligns theoretical concepts with their practical implications. 3. **Brute-Force Attack and Cryptanalysis**: Armed with foundational knowledge, students will explore the mechanics of brute-force attacks—an essential aspect of understanding attacker behavior. The course critically compares cryptanalysis techniques with brute-force methods, culminating in discussions about perfect secrecy. This section is particularly powerful, as it provides insights into the vulnerabilities of cryptographic systems and what defines true security. 4. **Computational Security and Side-Channel Attack**: The final module transitions students to a more practical view of security by discussing computational constraints and how they differ from information-theoretic models. It examines various side-channel attacks and the unintentional leakage of information from real-world implementations of cryptosystems. This segment effectively bridges the gap between theory and real-world applications, making cryptography applicable to everyday problems. ### Learning Experience and Recommendations The **"Cryptography and Information Theory"** course is not just informative but also engaging. The blend of theoretical knowledge with practical applications offers a balanced learning experience, and the modular structure allows students to build their understanding progressively. The course materials are well-organized, and the interactive assignments enable learners to apply their knowledge effectively. Whether you are a security enthusiast, a computer science student, or an industry professional looking to enhance your skills in data protection, this course is highly recommended. It is suitable for individuals at various levels of expertise—both newcomers to the field and those with prior knowledge will find valuable insights. By the end of the course, participants will gain a robust understanding of the principles, challenges, and methodologies in cryptography and information theory, along with practical skills to assess and enhance the security of digital systems. ### Conclusion In conclusion, Coursera's **"Cryptography and Information Theory"** course offers a rich educational journey into the world of data security. Its systematic approach, coupled with rich theoretical and practical insights, makes it a commendable choice for anyone aspiring to understand or work within the realms of cybersecurity and data protection. If you're looking to demystify cryptography and elevate your career in information security, this course is undoubtedly a step in the right direction.

Syllabus

Cryptography Overview

This module defines the technical terms in cryptography and introduce Alice, Bob, and Eve. To study the attacker Eve's perspective, we will describe Kerckhoff's Principle ("the attacker knows the system"), which defines the scope of the attacker knowledge (what is secret vs. what the attacker can know). We will also describe Security by Obscurity, which contrasts Kerckhoff's Principle.

This module studies information entropy to quantify randomness. Information entropy can be used to measure the strength of the key or the secret information that determines the security of a cryptosystem against an attacker who does not know the random key.

This module studies the attacker view whose objective is to learn the key and break the cryptographic protection using the key. First, we will define brute force attack and describe how to quantify the attacker effort for brute force attack. Next, we will contrast cryptanalysis and brute force attack. Lastly, we will discuss about perfect secrecy, which is immune to cryptanalysis and is a strong notion of security derived from information theory.

This module studies cryptography from the practical point of view. We will first define computational security, which relies on the fact that real world attackers are computationally limited unlike information theoretic security, e.g., one-time pad. We will then survey side channel attacks and unintentional information leakage from the physical implementations of cryptosystems.