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 on the command line

Producing an encryption key from a password on the command line can be done using the openssl kdf subcommand. This is a new subcommand that was added in OpenSSL 3.0. You can read its documentation on the openssl-kdf man page:

$ man openssl-kdf

Before deriving the key, let’s generate 128-bit salt:

$ openssl rand -hex 16
cf0e0acf943629ecffea41c87bab94d4

Now we can derive a 256-bit key suitable for symmetric encryption. Let’s use the Scrypt KDF. OWASP recommended brute-force-resistant settings and the password SuperPa$$w0rd:

$ openssl kdf \
  -keylen 32 \
  -kdfopt 'pass:SuperPa$$w0rd' \
  -kdfopt hexsalt:cf0e0acf943629ecffea41c87bab94d4 \
  -kdfopt n:65536 -kdfopt r:8 -kdfopt p:1 \
  SCRYPT
D0:3D:31:A1:A2:2A:F6:68:99:B3:02:22:60:3B:D7:21:5B:15:5B:80:2B:85:33:36:E6:3B:AB:F9:EE:8F:FE:C7

Note that the command-line argument containing the password...