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

Block cipher modes of operation

Block ciphers can operate in different encryption modes, also known as modes of operation. As we already know, block ciphers encrypt plaintext data block by block. Encryption modes specify how blocks of ciphertext are chained together. We are now going to review most popular operation modes.

Reviewing the Electronic Code Book mode

The simplest operation mode is Electronic Code Book (ECB). In this mode, each plaintext block is encrypted into a ciphertext block using only the encryption key, without using an IV or previous plaintext or ciphertext blocks. Then, the ciphertext blocks produced are concatenated.

The ECB mode can be illustrated by the following image:

Figure 2.3 – How ECB mode works

Image Source: Wikipedia, licensing: Public Domain

In the ECB mode, the same plaintext always produces the same ciphertext. It is a security issue because patterns in the plaintext are preserved in the ciphertext and are...