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 with ChaCha20-Poly1305

ChaCha20 is a more recent symmetric cipher designed by Daniel J. Bernstein in the mid-'00s. It's often used together with the Poly1305 hashing function (in this case, it's also called "message authentication code"), which was designed by the same cryptographer. The result of the combination of the two is the ChaCha20-Poly1305 authenticated stream cipher.

We talked about authenticated stream ciphers in the previous section when referring to AES-GCM: functionally, ChaCha20-Poly1305 serves the same purpose. Even in practice, they are used very similarly, as you'll see in the samples in this section.

ChaCha20-Poly1305 has been seeing an increase in interest and popularity in recent years since it's now implemented by a variety of applications and, more frequently, as a cipher for the TLS protocol (used by HTTPS). For example, Google offers support for it in all of its online services and in the Android...