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

How to sign programmatically

OpenSSL 3.0 provides the following APIs for digital signatures:

  • Legacy low-level APIs that consist of functions with algorithm-specific prefixes, such as RSA_, DSA_, and ECDSA_. These APIs have been deprecated since OpenSSL 3.0.
  • The EVP_PKEY API: This API is not deprecated but is still low level. It is more convenient to use a high-level API.
  • The EVP_Sign API: This API is high level but has some disadvantages. This API uses the key argument only after the whole input data has been read and hashed. Therefore, if there is a problem with the key, it will be discovered later rather than sooner. Another disadvantage is that this API is inflexible and does not allow you to set signing parameters to PKEY_CTX if the signature algorithm supports them. The OpenSSL documentation does not recommend this API.
  • The EVP_DigestSign API: This is a high-level API where drawbacks of the EVP_Sign API have been fixed. The OpenSSL documentation recommends...