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)
1
Part 1: Introduction
3
Part 2: Symmetric Cryptography
8
Part 3: Asymmetric Cryptography and Certificates
12
Part 4: TLS Connections and Secure Communication
16
Part 5: Running a Mini-CA

Accepting a TLS server connection on the command line

Follow these steps for accepting a TLS server connection on the command line:

  1. To accept a TLS server connection, we will use the s_server subcommand of the openssl tool. Its documentation can be found on its man page:
    $ man openssl-s_server
  2. We will provide a port number, a server certificate, and the corresponding server keypair to openssl s_server. That’s how we start a TLS server:
    $ openssl s_server \
        -port 4433 \
        -key server_keypair.pem \
        -cert server_cert.pem
  3. To check that our TLS server can accept connections and send and receive data over them, we can start a TLS client in another terminal window and connect to our TLS server:
    $ openssl s_client \
        -connect localhost:4433 \
        -verify_return_error \
        -verify_hostname localhost \
        -CAfile ca_cert...