Book Image

Essential Cryptography for JavaScript Developers

By : Alessandro Segala
Book Image

Essential Cryptography for JavaScript Developers

By: Alessandro Segala

Overview of this book

If you’re a software developer, this book will give you an introduction to cryptography, helping you understand how to make the most of it for your applications. The book contains extensive code samples in JavaScript, both for Node.js and for frontend apps running in a web browser, although the core concepts can be used by developers working with any programming language and framework. With a purely hands-on approach that is focused on sharing actionable knowledge, you’ll learn about the common categories of cryptographic operations that you can leverage in all apps you’re developing, including hashing, encryption with symmetric, asymmetric and hybrid ciphers, and digital signatures. You’ll learn when to use these operations and how to choose and implement the most popular algorithms to perform them, including SHA-2, Argon2, AES, ChaCha20-Poly1305, RSA, and Elliptic Curve Cryptography. Later, you’ll learn how to deal with password and key management. All code in this book is written in JavaScript and designed to run in Node.js or as part of frontend apps for web browsers. By the end of this book, you'll be able to build solutions that leverage cryptography to protect user privacy, offer better security against an expanding and more complex threat landscape, help meet data protection requirements, and unlock new opportunities.
Table of Contents (13 chapters)
Part 1 – Getting Started
Part 2 – Using Common Cryptographic Operations with Node.js
Part 3 – Cryptography in the Browser

An overview of hashing functions

Before we jump into the code, it's worth spending a few moments explaining what hashing functions are, how they are different from ciphers (which are functions that are used to encrypt and decrypt data), and their properties and uses.

Properties of hashing functions, and how they differ from encryption

While encryption is a two-way operation (you can encrypt a message and then decrypt it to get the original message once again), hashing is just one-way. That is, after you hash a message, you cannot retrieve the original plaintext in any way.

There are five defining characteristics of modern hashing functions:

  1. As we mentioned previously, you cannot retrieve the original message from its hash (also called a digest) as hashing functions are designed as one-way operations.
  2. Regardless of the size of the input message, the output hash has a fixed length. For example, SHA-256 hashes are always 32 bytes (256-bit) long, regardless of...