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

Symmetric encryption

We first encountered symmetric encryption in Chapter 4, Symmetric Encryption in Node.js, where we covered two ciphers: AES and ChaCha20-Poly1305.

In this chapter, we'll focus solely on AES, given that it's the only symmetric cipher that's standardized in the WebCrypto APIs and available on all browsers, with a few different modes of operation. We'll look at encrypting and decrypting data using AES-GCM and AES-CBC, and then we'll use AES-KW (RFC 3394) for wrapping and unwrapping keys.

While we won't cover ChaCha20-Poly1305, you can find several packages on npm that offer support for that, including implementations in pure JavaScript or that leverage native code via WebAssembly.

Encrypting and decrypting messages with AES

The WebCrypto APIs include two methods for encrypting and decrypting data:

  • crypto.subtle.encrypt(algorithm, key, data)
  • crypto.subtle.decrypt(algorithm, key, data)

Both methods have...