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

Understanding the openssl ca subcommand

The openssl ca subcommand can be useful for running a mini-CA inside an organization. This kind of CA can, for instance, issue certificates for internal servers. Using an internal CA saves costs compared to using an external commercial CA. But it is not the only advantage. Many internal servers should not be exposed to access from the internet. This limitation hinders automatic server checks from the external CAs, which are needed to issue cheap or free certificates. Also, in some cases, it is undesirable to expose knowledge about the existence or name of the internal servers. When ordering a certificate from an external CA, you have to expose the internal server’s name to the CA. Furthermore, the CA may publish the certificate information to a Certificate Transparency (CT) log, leading to even more unwanted information exposure about the company’s internal servers.

Another reason to have an internal CA is to issue client certificates...