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

Digital signatures

Digital signatures are the last class of cryptographic operations we learned about as we dedicated the biggest part of Chapter 6, Digital Signatures with Node.js and Trust, to them. Once again, in this section we'll revisit them by showing code samples that work in the browser using the WebCrypto APIs instead. Just as we did in Chapter 6, Digital Signatures with Node.js and Trust, we'll look at examples of calculating and verifying digital signatures using both RSA and ECDSA.

Digital signatures with the WebCrypto APIs

With the WebCrypto APIs, we can calculate a signature with the crypto.subtle.sign(algorithm, key, data) method. This returns a promise that resolves with an ArrayBuffer containing our signature's raw bytes, and it requires three parameters:

  • algorithm, the first argument, is an object that contains options for the digital signature algorithm to use. We'll see the details of this in the following sections for the RSA...