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 a Man in the Middle attack

A Man in the Middle (MITM) attack is an attack where an attacker both listens in on the transit traffic and changes it, trying to impersonate the receiver to the sender and the sender to the receiver.

Let’s demonstrate a possible attack for the scenario with Alice and Bob mentioned previously. Let’s suppose that Mallory acts as a Man in the Middle in order to recover the plaintext of the encrypted message that Alice wants to send to Bob. Then, the attack scenario will be as follows:

  1. Bob generates a keypair and sends his public key to Alice.
  2. Mallory generates her own keypair. She intercepts Bob’s public key sent to Alice and saves it for future use. Instead of Bob’s public key, Mallory sends her own public key to Alice, disguised as Bob’s key.
  3. Alice encrypts her message with Mallory’s public key, thinking that it is Bob’s public key. Alice then sends the encrypted message to...