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

Wrapping keys and best practices for encrypting large documents

In the previous section, we learned how symmetric keys are often derived from passphrases. Encrypting data with a passphrase or passcode that the user memorizes (or stores in a password wallet) is at the core of many, many solutions that leverage cryptography, such as to encrypt documents or files. The next time you unlock your laptop with a passphrase or your phone with a PIN, think about the key derivation functions and ciphers that are being executed!

By reading this chapter up to this point, you should already be able to build an application like the one we just described with Node.js. For example, you could use Argon2 to derive a key from a passphrase submitted by the user, and then use AES-GCM to encrypt and decrypt files.

However, passphrases are not static. That is to say that users do change their passphrases, sometimes because they want to rotate them, or sometimes because their previous one was compromised...