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

Assessing the security of cryptographic hash functions

The two most important types of attacks that can be performed on cryptographic hash functions are collision attacks and preimage attacks. A collision attack tries to find two messages that produce the same message digest, while a preimage attack aims to find a message that produces the predefined message digest. Performing a collision attack is easier than performing a preimage attack on the same hash function because the message search is not limited to a single target message digest.

The security level of a cryptographic hash function is the computational complexity of the collision attack. The security level is measured in security bits, similar to the security level of symmetric encryption algorithms. For example, if the complexity of the collision attack is 2,128 hash evaluations, then the security level is 128 bits.

The security level of a cryptographic hash function depends on the size of its output message digest...