Book Image

Demystifying Cryptography with OpenSSL 3.0

By : Alexei Khlebnikov
Book Image

Demystifying Cryptography with OpenSSL 3.0

By: Alexei Khlebnikov

Overview of this book

Security and networking are essential features of software today. The modern internet is full of worms, Trojan horses, men-in-the-middle, and other threats. This is why maintaining security is more important than ever. OpenSSL is one of the most widely used and essential open source projects on the internet for this purpose. If you are a software developer, system administrator, network security engineer, or DevOps specialist, you’ve probably stumbled upon this toolset in the past – but how do you make the most out of it? With the help of this book, you will learn the most important features of OpenSSL, and gain insight into its full potential. This book contains step-by-step explanations of essential cryptography and network security concepts, as well as practical examples illustrating the usage of those concepts. You’ll start by learning the basics, such as how to perform symmetric encryption and calculate message digests. Next, you will discover more about cryptography: MAC and HMAC, public and private keys, and digital signatures. As you progress, you will explore best practices for using X.509 certificates, public key infrastructure, and TLS connections. By the end of this book, you’ll be able to use the most popular features of OpenSSL, allowing you to implement cryptography and TLS in your applications and network infrastructure.
Table of Contents (20 chapters)
Part 1: Introduction
Part 2: Symmetric Cryptography
Part 3: Asymmetric Cryptography and Certificates
Part 4: TLS Connections and Secure Communication
Part 5: Running a Mini-CA


In this chapter, we will learn about message authentication codes (MACs), also known as authentication tags. MACs are used in popular secure network protocols, such as TLS, SSH, and IPsec in order to establish both the integrity and authenticity of the transmitted data. They are also used in proprietary network protocols, for example, in financial software, for the same purpose. Additionally, MACs can be used in non-networked authenticated encryption, as we demonstrated in Chapter 2, Symmetric Encryption and Decryption. Another application of MAC is as the basis of some key derivation functions, such as PBKDF2. Key derivation will be covered in more detail in Chapter 5, Derivation of an Encryption Key from a Password. We will learn how to calculate a MAC using both the command line and C code.

In this chapter, we are going to cover the following topics:

  • What is a MAC?
  • Understanding MAC function security
  • HMAC – a hash-based MAC
  • MAC, encryption...