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

Using TLS on non-standard sockets

To learn how to use TLS on a non-standard socket, we are going to write a small tls-client-memory-bio program.

Our tls-client-memory-bio program will be based on the tls-client program from Chapter 9, Establishing TLS Connections and Sending Data over Them. We are going to take the tls-client program source code and change it to work via memory BIOs.

We are going to change quite a lot in the tls-client source code. For instance, we are not going to use an SSL BIO this time. An SSL BIO is a wrapper around an SSL object. In the previous example programs, it was convenient to use an SSL BIO, which was automatically chained with a connect BIO. This time, we are not going to automatically chain with a connect BIO. Instead, we will use I/O directly on an SSL object, using functions such as SSL_read() and SSL_write() instead of BIO_read() and BIO_write(). Using I/O directly on the SSL object will not only simplify the code but will also demonstrate...