Authors: Dr. Anjali Singhal, Ms. Archana Agarwal, Mr. Ajay Kumar, Dr. Alka Singhal, and Ms. Swapna Singh

ISBN: 978-81-69857-72-7

DOI: https://doi.org/10.59646/826

Date of Publication: September 23, 2026

Preface

Cryptography and Cybersecurity: Fundamentals, Algorithms, Applications and Modern Cyber Defense is designed to provide a comprehensive and technically oriented foundation for understanding how information is protected in modern digital environments. As cyber threats continue to evolve across computer networks, cloud platforms, web applications, mobile systems, Internet of Things (IoT) environments, and emerging intelligent infrastructures, cryptography and cybersecurity have become essential components of secure computing. This book brings together the mathematical principles, cryptographic algorithms, security mechanisms, practical applications, and cyber defense techniques required to understand and address contemporary security challenges.

The book begins with the fundamental concepts of information security and cybersecurity, introducing the CIA triad, authentication, authorization, accountability, security assets, threats, vulnerabilities, risks, attacks, and defense strategies. The mathematical foundations required for cryptographic computation are then developed through number theory, prime numbers, divisibility, greatest common divisors, modular arithmetic, modular inverses, Fermat’s and Euler’s theorems, the Chinese Remainder Theorem, and the discrete logarithm problem. These concepts establish the theoretical foundation necessary for understanding modern cryptographic algorithms.

The subsequent chapters systematically examine classical and contemporary cryptographic techniques. Classical substitution and transposition ciphers provide an introduction to encryption and cryptanalysis, while symmetric-key cryptography covers DES, Triple DES, AES, stream ciphers, ChaCha20, block cipher modes, authenticated encryption, and key management. Public-key cryptography introduces RSA, Diffie–Hellman, ElGamal, digital signatures, and hybrid cryptographic systems. Hash functions, MACs, HMAC, digital signatures, password hashing, and salting are discussed to demonstrate how integrity, authentication, and non-repudiation are achieved in practical systems. Elliptic Curve Cryptography, ECDH, ECDSA, secret sharing, zero-knowledge proofs, and introductory concepts of homomorphic encryption further extend the discussion toward modern cryptographic applications.

The book also connects cryptographic principles with practical security systems. Network and web security topics include firewalls, intrusion detection and prevention systems, VPNs, HTTPS, TLS, digital certificates, PKI, SQL injection, cross-site scripting, CSRF, and secure API communication. Identity and access management is addressed through digital identity, multifactor authentication, biometrics, single sign-on, OAuth, OpenID Connect, RBAC, ABAC, privileged access management, and Zero Trust security. The cyber defense section introduces ethical hacking, reconnaissance, vulnerability assessment, penetration testing, digital forensics, malware analysis, incident response, SIEM, threat intelligence, business continuity, and cyber resilience.

Particular attention is given to emerging technologies that are reshaping cybersecurity. The role of artificial intelligence and machine learning in intrusion detection, malware analysis, phishing detection, and adversarial machine learning is examined alongside blockchain security, smart contracts, IoT security, cloud-IoT environments, quantum computing, quantum key distribution, and post-quantum cryptography. These topics provide readers with an understanding of how cybersecurity is adapting to rapidly changing computational and technological landscapes.

A dedicated practical section strengthens the theoretical discussion through laboratory exercises and case studies involving classical cipher implementation, AES, RSA, SHA-256, digital signatures, Diffie–Hellman key exchange, password security, network security, web vulnerabilities, and incident response. Worked examples, exercises, security scenarios, and practical investigations are incorporated throughout the book to support analytical thinking and hands-on learning. The book is intended for undergraduate and postgraduate students of Computer Science, Information Technology, Cybersecurity, Engineering, and related disciplines, as well as researchers, educators, security practitioners, and professionals seeking a structured reference to cryptography and modern cyber defense. Overall, the book aims to bridge mathematical foundations, algorithmic understanding, security architecture, practical implementation, and emerging cybersecurity technologies within a unified framework.