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

Calculating digests and generating identifiers

Let's start by looking at how to use hashing functions with Node.js for the first two use cases presented previously – calculating the digests of messages or files to guarantee their integrity and generating unique identifiers.

For both these situations, the modern, recommended hashing function is SHA-256, which is part of the SHA-2 family. As its name suggests, SHA-256 returns a hash that is 256-bit in length or 32 bytes.

Other variants in the SHA-2 family exist, such as SHA-384 or SHA-512, which create hashes of 384 or 512 bits (48 or 64 bytes), respectively. These, although far less common, can be useful in cases where additional resistance to collision is needed, as we'll explore at the end of this chapter.

Hashing a short message or string

With Node.js, routines to calculate SHA-256 hashes are built into the crypto module. Using them requires just a few lines of code, as shown in the following sha256Digest...