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

Deriving a key from a password programmatically

We are going to implement the kdf program, which will derive a key from a password.

Our key derivation program will take two command-line arguments:

  1. Password
  2. Hex-encoded salt

We are not going to take the N, r, and brute-force-resistant Scrypt parameters because because we want to simplify our example program and its usage. Instead, we are going to use OWASP-recommended settings.

OpenSSL 3.0 provides the following APIs for key derivation:

  • The PKCS5_PBKDF2_HMAC(), PKCS5_PBKDF2_HMAC_SHA1(), and EVP_PBE_scrypt() legacy functions, specific to particular KDFs.
  • The EVP_PKEY API. This API is intended for use with asymmetric cryptography and contains the EVP_PKEY_derive() function. That function is mostly intended for non-password-based key derivation during key exchange operations in secure network protocols, such as Diffie-Hellman key exchange, but also supports password-based key derivation using the Scrypt...