Introduction to Cryptography

Cryptography is the practice and study of techniques for secure communication in the presence of adversaries. This book provides a comprehensive introduction to both classical and modern cryptographic methods.

What is Cryptography?

Cryptography involves creating mathematical algorithms and protocols that allow for:

• Confidentiality: Ensuring that information is accessible only to those authorized to have access
• Integrity: Maintaining the accuracy and completeness of data
• Authentication: Verifying the identity of communicating parties
• Non-repudiation: Preventing parties from denying they sent or received messages

Historical Context

The history of cryptography spans thousands of years, from ancient techniques like the Caesar cipher used by Roman generals to modern quantum-resistant algorithms designed to protect against future quantum computers.

Modern Applications

Today, cryptography is essential for:

• Online banking and e-commerce
• Secure messaging applications
• Blockchain and cryptocurrencies
• Internet protocols (HTTPS, TLS)
• Mobile device security
• Cloud computing security

About This Book

This book covers both theoretical foundations and practical implementations of cryptographic systems. Each chapter includes mathematical explanations, code examples, and real-world applications.

The content is organized from basic concepts to advanced topics, making it suitable for students, developers, and security professionals looking to deepen their understanding of cryptography.

Author: Md. Al-Amin Khandaker, Ph.D.
Cybersecurity Engineer at ITK Engineering GmbH